# Question about Blu-DRO/Touch DRO



## COMachinist (Apr 26, 2018)

Have a question about this accessory. I have the igagaging absolute plus stainless steel rules. I have an android tablet as well as my phone. I’m installing this  now, it will be nice to use the tablet which is a 10” display. Has any one here done this up grade to their igaging. I want to hear about any problems or difficulty using this system. When I got the gages ready to plug in i found out that the 36” rule for the Z axis has an out of date mini usb conector will the X axis has a micro usb which works with the Blu-DRO hub. I have tried get in touch with igaging but so far no responce. What I m thinking is using a mini usb female to micro male adapter to conect to the hub. The hub has other banks so you can use one hub and app on other machines, like the lathe, mill and a surface grinder, realy any thing with a igaging plus dro on it. Im not associated with Blu-dro or touch dro in any way just. Looking for other users.
Thanks
CH


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## RJSakowski (Apr 26, 2018)

I built the interface based on Yuriy's original Touch DRO.    I would think that an adapter would work fine.
The only issue that I have is that sometimes in shutting down my 602, I get a line spike which messes up the reading.  It doeswn't haqppen if I run from a battery but if I use a power supply, it occasionally occurs. I will probably need to build a custom power supply to totally eliminate the problem.  Or change the OEM motor to a VFD.


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## COMachinist (Apr 26, 2018)

I noticed some instability on the display when running the lathe the display will kind of jitter a bit. What I found out was the wall wort was piking up some noise. I found an old ryobi transformer type 9vdc at 2 amps. That solved the noise problem. The display is now nice and stable. I am suprised that it very accurate and repeatable. It shows repeatablity at .0008”. Nice to have that big 10 display. With old eyes like mine.
CH


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## tweinke (Apr 26, 2018)

I have one I built with the MSP430 board on my lathe and also with the premade board on my mill. The premade board is much more stable. I did read that Yuri recommended at one time to plug in the power supply to a different circuit then the machine which is what I have done with the lathe and that has made a noticeable difference too.


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## COMachinist (May 1, 2018)

Well I have some time with this unit and I must say, I don’t think it is ready forprime time in the shop. While it s a great idea I think it needs more development time. It would s intirely to unstabile in a shop enviroment. I have LED lighting in my shop, because it is much better for an unheated shop and it only has 1 window for added light. I also have a domore grinder plus about 4 grinders for different griding of metal cutting plus the 2 VFDs on the a 2x72 grinder and the mill, I use a lot. This thing goes nuts when the first lights come on and it will not stay conected to and blue tooth, display. The screen goes in to convlutions every time my cell rings or the old motor on the lathe this is used on, starts. Forget it if the PM-932m- PDF mill starts with the lathe next to it. The air compessor does not do it any good either. I think i will just go back to my igaging absolute read outs. They are fine and happy in the shop. I just had a power up grade this winter to 200 amp service. So i know it is plenty of stabile power. It doesn’t matter weather it’s paired to my Galaxy S7 or the Android tablet. It will not stay connected. My phone works fine and so does the radio, so I don’t know what the problem is. Must be some kind of noise that does not affect and thing else.
Oh well gave it a chance.
CH


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## Briney Eye (May 1, 2018)

I'm quite happy with both of my TouchDRO installations, but I didn't expect a turnkey solution.  It's a platform for someone interested in a DIY project, and the app itself works quite well for someone willing to deal with the issues.  A lot of "wall wart" power supplies are extremely noisy direct line switchers that interfere with the Bluetooth connection.  I've saved a box full of them over the years and found ones that worked.  The scales that TouchDRO works with are designed to run on batteries, isolated from the world, and lack any power supply decoupling.  Generally speaking, the stability issues can be solved by installing decoupling capacitors in the read heads (I used 0.1uf ceramics).  Opening the heads, tracing signals and finding the correct points to tack the capacitor leads to exceeds many people's expertise.  I enjoy solving that sort of problem, which is why I've been making a living in R&D for nearly 40 years.

If I had another machine to add readouts to I wouldn't hesitate to use TouchDRO again, but it's not for everyone.


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## COMachinist (May 2, 2018)

Briney Eye said:


> I'm quite happy with both of my TouchDRO installations, but I didn't expect a turnkey solution.  It's a platform for someone interested in a DIY project, and the app itself works quite well for someone willing to deal with the issues.  A lot of "wall wart" power supplies are extremely noisy direct line switchers that interfere with the Bluetooth connection.  I've saved a box full of them over the years and found ones that worked.  The scales that TouchDRO works with are designed to run on batteries, isolated from the world, and lack any power supply decoupling.  Generally speaking, the stability issues can be solved by installing decoupling capacitors in the read heads (I used 0.1uf ceramics).  Opening the heads, tracing signals and finding the correct points to tack the capacitor leads to exceeds many people's expertise.  I enjoy solving that sort of problem, which is why I've been making a living in R&D for nearly 40 years.
> 
> If I had another machine to add readouts to I wouldn't hesitate to use TouchDRO again, but it's not for everyone.


Sorry but I disagree with your post almost in it entirety. First off I did not buy the DIY boards I bought the Blu-DRO 4 channel box with tach input. I was told to buy igaging aboslute Plus units that do run on wall wart or batteries. Be sides the only thing that is used from the igaging DRO’s is the stainless rules which are made to run with the igaging plus units that run on ac or battery power. The problem is with the electronics and the software. What makes frustrating is that igaging has no support and selling old out dated rules with both plug types and no efort to help.  Sorry but I feel this option is not workable with out electronics up dates. Not in a shop environment.
CH


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## 9t8z28 (Aug 25, 2018)

I have read that switching to an older wall-wart transformer fixes most of these issues.  I do have the problem with the tenths digit being slightly glitchy some of the time.  The wall-wart is supposed to fix this.  The power supply they include with the Bu-Dro kit is the problem.  Yes, flourescent lights can effect the readouts and I am not trying to be rude but they are outdated and on their way out.  LED’s are the way to go.   Yes I understand it can be expensive to switch to LED’s  and is not always practical but unfortunately the florescencent are part of the problem.
 Try running the power supply from a different wall outlet or isolate it from any power source that is sharing power with a flourescent light.  Lastly, sometimes the motor of these machines are not perfectly grounded any that can interfere with the scales.  You can isolate the scale with a non conductive material.  This helps tremendously.  Oh and I also forgot, make sure the scale cables are not running or crossing a power supply or motor leads.  This will effect them as well.   I love my Blu-Dro and iGaging scales.  They are very accurate and very very repeatable.  I use them both on my mill which has a transplanted treadmill motor and my lathe with ony the occassional glitching problem on the mill, which honestly happens very little  to the point that the wall-wart tranformer is not a must-do-now-mod.   I also run all types of machinery in the background while the mill and lathe are running and they cause no interference


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## BaronJ (Aug 25, 2018)

Hi Guys,

Any electrical equipment, even the TAB 9 itself will generate some kind of interference !  And as you have already discovered fluorescent lights and switch mode power supplies as well.

The real issue is preventing this interference from causing problems.  Screening is the way to reduce radiated interference, line borne interference can be reduced by filtering.  You need to start by finding out which type you have and which is the worse.  Then tackle that first.


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## 9t8z28 (Aug 25, 2018)

How can you tell the difference between the switching and non-switching power sources?  I am on eBay trying to find a tranformer style wall wart and don’t want to buy the wrong thing  





BaronJ said:


> Hi Guys,
> 
> Any electrical equipment, even the TAB 9 itself will generate some kind of interference !  And as you have already discovered fluorescent lights and switch mode power supplies as well.
> 
> The real issue is preventing this interference from causing problems.  Screening is the way to reduce radiated interference, line borne interference can be reduced by filtering.  You need to start by finding out which type you have and which is the worse.  Then tackle that first.


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## vtcnc (Aug 25, 2018)

I did the DIY version and had to ground the system to a water pipe to get the interference to stop.


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## BaronJ (Aug 26, 2018)

Hi Guys,

Easy !  Weight.  Switching power bricks don't have a heavy transformer in them, linear ones do.  If you get one each of similar ratings together you will see what I mean.


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## Briney Eye (Aug 26, 2018)

9t8z28 said:


> I have read that switching to an older wall-wart transformer fixes most of these issues.  I do have the problem with the tenths digit being slightly glitchy some of the time.  The wall-wart is supposed to fix this.  The power supply they include with the Bu-Dro kit is the problem.  Yes, flourescent lights can effect the readouts and I am not trying to be rude but they are outdated and on their way out.  LED’s are the way to go.   Yes I understand it can be expensive to switch to LED’s  and is not always practical but unfortunately the florescencent are part of the problem.
> Try running the power supply from a different wall outlet or isolate it from any power source that is sharing power with a flourescent light.  Lastly, sometimes the motor of these machines are not perfectly grounded any that can interfere with the scales.  You can isolate the scale with a non conductive material.  This helps tremendously.  Oh and I also forgot, make sure the scale cables are not running or crossing a power supply or motor leads.  This will effect them as well.   I love my Blu-Dro and iGaging scales.  They are very accurate and very very repeatable.  I use them both on my mill which has a transplanted treadmill motor and my lathe with ony the occassional glitching problem on the mill, which honestly happens very little  to the point that the wall-wart tranformer is not a must-do-now-mod.   I also run all types of machinery in the background while the mill and lathe are running and they cause no interference



LED task lights can be the very worst offenders for generating noise, but it's luck-of-the-draw.  I have a gooseneck LED that generates tremendous amounts of electrical noise, and one on an articulated arm that's perfectly quiet.  I haven't noticed any issues so far with the LED replacements for incandescent bulbs.

The best solution to TouchDRO stability issues is installing decoupling capacitors in the scales themselves.  After I did that to mine they were very stable (even with the gooseneck LED on).  This shows the mod to a Shars scale (and yes, I should have trimmed the leads):


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## JPigg55 (Aug 26, 2018)

I've contacted Bill from iGaging in the past, he's of no help for technical support.
All he will do is tell you to send him your question via email and he'll forward it to his supplier.
Whether he forwards it or not, I'm not sure, but no answers will be forthcoming. They consider Yuriy and Touch DRO as competitors. I'm unsure why since they don't offer a true DRO, just displays for their scales.
One thing to check is if the USB cords are shielded. Some from iGaging are and some are not.
Here's a source for the obscure cable types iGaging uses: http://www.dcables.net/
It's difficult to find some of the cables like the male to male mini-B cords, but they do have them.


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## 9t8z28 (Aug 26, 2018)

This is good to know.  My Blu-Dro came with the cheap switching style.   I’ve also heard that these switching types are not supposed to get hot but mine does.   I looked and found 2 heavy power bricks in a box of old power supplies that no longer have a use.  Good thing I hung onto these.   I knew they would serve a purpose one day.  One is 12V and the other is 6V.   I am going to cut the cord off of each one and try both of them since I need two of them for the 2 Blu-Dro’s I have.   Thanks BaronJ.  





BaronJ said:


> Hi Guys,
> 
> Easy !  Weight.  Switching power bricks don't have a heavy transformer in them, linear ones do.  If you get one each of similar ratings together you will see what I mean.


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## 9t8z28 (Aug 26, 2018)

I have heard of this before but never really looked into it much.  Where do you get these decoupling capacitors?   How do I know which ones to get ?   Thanks for posting this 





Briney Eye said:


> LED task lights can be the very worst offenders for generating noise, but it's luck-of-the-draw.  I have a gooseneck LED that generates tremendous amounts of electrical noise, and one on an articulated arm that's perfectly quiet.  I haven't noticed any issues so far with the LED replacements for incandescent bulbs.
> 
> The best solution to TouchDRO stability issues is installing decoupling capacitors in the scales themselves.  After I did that to mine they were very stable (even with the gooseneck LED on).  This shows the mod to a Shars scale (and yes, I should have trimmed the leads):
> 
> View attachment 274509


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## RJSakowski (Aug 26, 2018)

Briney Eye said:


> LED task lights can be the very worst offenders for generating noise, but it's luck-of-the-draw.  I have a gooseneck LED that generates tremendous amounts of electrical noise, and one on an articulated arm that's perfectly quiet.  I haven't noticed any issues so far with the LED replacements for incandescent bulbs.
> 
> The best solution to TouchDRO stability issues is installing decoupling capacitors in the scales themselves.  After I did that to mine they were very stable (even with the gooseneck LED on).  This shows the mod to a Shars scale (and yes, I should have trimmed the leads):
> 
> View attachment 274509


After reading your modification, I decided to modify mine.  I used a .05 mfd disk  and a 4 mfd electrolytic in parallel.  The reasoning is that the disk capacitor has a better high frequency response and the electrolytic is capable of dealing with any longer duration voltage shifts.  Rather than  soldering to the ground plane as you have done, I decided to use the soldered mounting for the USB jack directly above the capacitor in your photo.

I had no inteference from fluorescent lighting or external voltage spikes.  ?My readings would jump when I shut the lathe motor off.  Moving the Arduino power supply yto a different outlet would diminish the frequency of the glitches and running on battery power would eliminate them but it was  bither to be using a battery for power.  

I will be watching to see if I have any further glitches.


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## BaronJ (Aug 27, 2018)

Hi Guys,

Just about any 1000pf to 5000pf ceramic capacitor will do for that purpose.  If you are going to use any on high voltage equipment, motor commutators, relay contacts,  make sure that you use 500 volt or greater rating.

My mill motor, which uses brushes, now has a pair wired across the commutator.  This completely kills the noise that used to come from it.  I also fitted a mains suppression filter inside the control box.  That one I salvaged from a dead computer PSU.

Fortunately non of the fluorescent lighting in the shop produce any interference.  I've got a mixture of normal and electronic ballasted ones.


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## homebrewed (Aug 27, 2018)

I have 3 of the older igaging scales on my mini mill.  I've gone around and around with the noise issue.  Here are things I've found to be helpful:

1.  Shielding the cables.  The cables that came with my scales were not shielded.  I bought some copper braid and put it over the cables, then soldered wires from the shield to the DRO ground (I had to get inside the DRO remote receiver units to do it).  Yuriy's Toys has a lot on this issue, as well.
2.  Bypass capacitors across the read head's internal power supply  connections.  I used 1uf plastics to good effect.  On mine, Vcc and Gnd were clearly marked on the PCB so it was easy to do.
3.  Do not use the provided mounting hardware, unless you insulate the scale from the hardware using electrical tape.  I made my own mounts out of Acetal.

If the readings start to jump around after awhile, that usually is an indication that the batteries are getting low.  Low supply voltage increases the unit's noise susceptibility.

I bought a wall-wart from Jameco that has a 9VAC output, so I know it has an old style 60Hz transformer in it, so no noise from a switcher; and good isolation from the power line.  I've got diode bridges, capacitors and voltage regulators left over from my days as an electronics engineer (plus some perf board) so I'm going to make a power supply to get rid of the batteries.  Hopefully the extra wires don't act as antennae (but I do have more shielding braid if needed).

For those who don't want to make this kind of power supply, FYI two series-connected D cells would outlast the CR2032's in the DROs by a substantial amount.  Places like Jameco sell battery holders for a wide variety of battery configurations.


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## Briney Eye (Aug 27, 2018)

9t8z28 said:


> I have heard of this before but never really looked into it much.  Where do you get these decoupling capacitors?   How do I know which ones to get ?   Thanks for posting this





BaronJ said:


> Hi Guys,
> 
> Just about any 1000pf to 5000pf ceramic capacitor will do for that purpose.  If you are going to use any on high voltage equipment, motor commutators, relay contacts,  make sure that you use 500 volt or greater rating.
> 
> ...



I used some cheap ceramics, 0.01uf, but 0.1uf or 0.001uf would probably work fine.  You can get them from a number of places.  Adafruit sells a ten-pack of 0.1uf's.  Sparkfun sells a whole kit of different values, including electrolytics.  I've gotten kits from Amazon.  As previously mentioned, you could parallel a bulk electrolytic and a small ceramic, but a single ceramic in the head and the bulk capacitance on the TouchDRO board does the job for me.

The problem exists because the scales consume minuscule current so that they can run on a coin cell for a year or more.  The high supply impedance of the logic chip in the read head makes it very susceptible to noise.  The manufacturers can get away with no decoupling in the head because the scales are normally running on batteries and isolated.

Fiddling with the capacitance on Yuriy's TouchDRO boards might provide a fix, but I've seen long power supply cables cause nasty problems.  I _always_ decouple as close to the power pin of an IC as I can get as part of the overall power system design, which involves an array of capacitance types and values chosen to broaden the bandwidth of the power supply decoupling scheme.  (I also always design with very low impedance power supply plane layers, but those design decisions have already been made for us here.)


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## RJSakowski (Aug 28, 2018)

I added decoupling capacitors inside my Arduino box and they decreased the number if glitches but didn't entirely eliminate them.  I also tried ferrite chocks on the power supply cable for the Arduino and on the lathe motor cord.  Also tried was using a different mains circuit.  My cables from the scale pickups run through flexible stainless steel conduit, grounded at both ends due to the mounting.  There is about 4" of exposed cable at either end.

I should say that the Arduino circuit was breadboarded on perf board using one of the Arduino shield  prototypong boards  and mounted in a Bakelite box so it is not the neatest design regarding  suppression of interference.

With the decoupling capacitors added to the scale pickups, I haven't seen any glitches.  However, the ionsidious nater of intermittants is just when you think you solved the problem, they show up.  Time will tell.  Fingers crossed.


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## 9t8z28 (Aug 29, 2018)

I do not understand any of these electronics terms, abbreviations, uf’s, pf’s, electrolytics, ceramics, plastics, decouple, etc.
Can anyone explain in laymans terms what these things are that Briney Eye posted a picture of and where to get them?  Decoupling Capacitors?  What value do I need, if thats how they are distinguished ?  I know nothing about electronics so I would need someone to recommend a particular part.   You don’t have to go into detail explaining what they do, just what I need to fix the unstable jumping readouts.   I already got 2 tranformers I had laying around to use on my 2 Blu-Dro units for my mill and my lathe.  They helped but the problem is not gone.  One is 9V and the other is 6V but they both put out 12V when tested with my digital multi meter. 
Also, where do I get shielded USB cables.   Everywhere I look online, they all say that they are shielded.   If I have to cut the ends off and reattach the correct ends I can do that.


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## ttabbal (Aug 29, 2018)

USB cables are all shielded if you buy a remotely decent one. It's entirely possible that the cables that come with the scales are not as they would not need to pass certification tests or high speed data. 

Capacitors are simple enough, but are you able to solder on a PCB without damaging it? If you don't do much with electronics, you may do more harm than good trying to learn on the scales. 0.01uF/16V ceramic caps are widely used for decoupling and are available at just about any electronics supplier. Even Radio Shack kept them around. 

Power supplies can read a higher voltage than expected when they are not loaded. Go with the label or test while they are powering something. Also make sure that they can supply enough current. Issues in power levels can cause all kinds of problems with electronics. If in doubt, buy a new one with the proper specs from a reputable supplier. This alone can make a huge difference. I've repaired a lot of gear just by replacing marginal power supplies.


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## BaronJ (Aug 29, 2018)

Hi Guys,

Beware, it is easy to kill very low current draw electronics using unloaded linear power bricks !  One big advantage of switch mode power supplies is that they are output voltage stable,  in the sense that if it says 6 volts on the label, it will be 6 volts on the output.

A linear power supply, ie one with a transformer in it could actually have an unloaded output of twice the label voltage rating.


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## homebrewed (Aug 29, 2018)

BaronJ said:


> A linear power supply, ie one with a transformer in it could actually have an unloaded output of twice the label voltage rating.



When referring to a linear power supply, the "linear" part of the name indicates it has a linear voltage-regulation circuit in it.  An UNregulated supply will definitely have a large variation in its output that depends on the load.  Plus a lot of ripple.  If I bought a "linear power supply" that exhibited a large variation in its output voltage due to the load (assuming the supply isn't going into current limit), I would return it as defective.

So, although linear supplies do have transformers in them, that does NOT mean they are unregulated.  It would be entirely feasible to make a linear power supply that does not have a transformer in it,  but the efficiency would be pretty low; and you'd lose isolation from the AC line.  And if the linear regulator failed you could end up with 120+ volts coming out of it!  I'd say that's a good argument for putting a nice step-down transformer in there


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## Briney Eye (Aug 29, 2018)

9t8z28 said:


> I do not understand any of these electronics terms, abbreviations, uf’s, pf’s, electrolytics, ceramics, plastics, decouple, etc.
> Can anyone explain in laymans terms what these things are that Briney Eye posted a picture of and where to get them?  Decoupling Capacitors?  What value do I need, if thats how they are distinguished ?  I know nothing about electronics so I would need someone to recommend a particular part.   You don’t have to go into detail explaining what they do, just what I need to fix the unstable jumping readouts.   I already got 2 tranformers I had laying around to use on my 2 Blu-Dro units for my mill and my lathe.  They helped but the problem is not gone.  One is 9V and the other is 6V but they both put out 12V when tested with my digital multi meter.
> Also, where do I get shielded USB cables.   Everywhere I look online, they all say that they are shielded.   If I have to cut the ends off and reattach the correct ends I can do that.



Capacitance is a measure of electrical charge, expressed in farads.  A microfarad is abbreviated uf (or uF), a nanofarad is nf, a picofarad is pf.  Ceramic capacitors are two-terminal devices made like a layer cake of "interdigitated" (like lacing your fingers together) conductive and insulating layers.  The insulator is a ceramic material.  Electrolytics are typically wound up like a jelly roll.  A layer of foil is wound up together with a layer of insulator.  The insulator can be made of different things.  There is also some kind of solid, liquid or gel electrolyte in there, but if you care you can google it.

Decoupling refers to providing a low-impedance reservoir of charge (generally a capacitor or capacitors) close to a component.  It "filters" the power and takes the noise out (it's really more complicated than that, but filtering is a good enough analogy).

In the picture I put up, the round, reddish thing with two wires is a ceramic capacitor.  I had it in my stash, and probably bought it from Radio Shack twenty years ago.  Here are some other ceramic shapes.  They generally don't care which direction they're installed:
















Here's what electrolytics look like.  They have polarity markings because they care which direction they're put in:















If you're going to do this, for simplicity's sake, I would recommend buying a kit from Sparkfun.  Since you have no electronics experience, open one of your read heads and post an extreme closeup of the circuit board inside.  We need to be able to read the silkscreen to tell you where to install the capacitor.  You will need a small soldering iron and some electronic solder.  Install one of the 10nf (nanofarad) ceramic capacitors like the first picture between "ground" and power (might be labeled GND and VCC).

Or find a friend who understands this stuff to help you.  Don't worry about your cables until you've tried this first.  Best of luck.


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## 9t8z28 (Aug 29, 2018)

Thank you very much for taking the time to explain all of this in great detail.  It is much appreciated.  
I will take the cover off of one of my iGaging read heads and post a picture.  
  When selecting a 10nf ceramic capacitor do I have to be concerned with the voltage ?   Just doing a quick search on Ebay shows different voltages.   Some are 100V, 103V, 1,000V and so on.  
 Yes I am capable of soldering small parts.  I have made some repairs to some of my car audio Kenwood head units and Amps, replaced and resoldered a CD spindle motor, replaced ribbon cables, soldered small wires to a board to fix broken  RCA cables.   As I said previously, I don’t really know much about electronics but if I know what the problem is and someone has diagnosed it, I can repair it.  



Briney Eye said:


> Capacitance is a measure of electrical charge, expressed in farads.  A microfarad is abbreviated uf (or uF), a nanofarad is nf, a picofarad is pf.  Ceramic capacitors are two-terminal devices made like a layer cake of "interdigitated" (like lacing your fingers together) conductive and insulating layers.  The insulator is a ceramic material.  Electrolytics are typically wound up like a jelly roll.  A layer of foil is wound up together with a layer of insulator.  The insulator can be made of different things.  There is also some kind of solid, liquid or gel electrolyte in there, but if you care you can google it.
> 
> Decoupling refers to providing a low-impedance reservoir of charge (generally a capacitor or capacitors) close to a component.  It "filters" the power and takes the noise out (it's really more complicated than that, but filtering is a good enough analogy).
> 
> ...


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## RJSakowski (Aug 29, 2018)

9t8z28 said:


> Thank you very much for taking the time to explain all of this in great detail.  It is much appreciated.
> I will take the cover off of one of my iGaging read heads and post a picture.
> When selecting a 10nf ceramic capacitor do I have to be concerned with the voltage ?   Just doing a quick search on Ebay shows different voltages.   Some are 100V, 103V, 1,000V and so on.
> Yes I am capable of soldering small parts.  I have made some repairs to some of my car audio Kenwood head units and Amps, replaced and resoldered a CD spindle motor, replaced ribbon cables, soldered small wires to a board to fix broken  RCA cables.   As I said previously, I don’t really know much about electronics but if I know what the problem is and someone has diagnosed it, I can repair it.


My iGaging pickups are running on about 3.5 volts so any ceramic disk capacitor should work.  It doesn't hurt to have a higher voltage rating.  The capacitor will be physically larger than the same value in a lower voltage rating.


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## 9t8z28 (Aug 30, 2018)

Let me make sure I’m understanding this, you’re saying that it doesn’t matter what nf value or voltage value ceramic disk capacitor I use,  as long as the voltage rating of the capacitor is higher than the voltage that is supplied to the read head?   If I am understanding that correctly that means that these 100V ceramic disk capacitors will work just fine.  

I am using Blu-Dro controllers and I am unaware of the voltage that is supplied to the read heads.  I can only assume that its 3.5V which is the same as Yuri’s Arduino board.  



RJSakowski said:


> My iGaging pickups are running on about 3.5 volts so any ceramic disk capacitor should work.  It doesn't hurt to have a higher voltage rating.  The capacitor will be physically larger than the same value in a lower voltage rating.


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## RJSakowski (Aug 30, 2018)

9t8z28 said:


> Let me make sure I’m understanding this, you’re saying that it doesn’t matter what nf value or voltage value ceramic disk capacitor I use,  as long as the voltage rating of the capacitor is higher than the voltage that is supplied to the read head?   If I am understanding that correctly that means that these 100V ceramic disk capacitors will work just fine.
> 
> I am using Blu-Dro controllers and I am unaware of the voltage that is supplied to the read heads.  I can only assume that its 3.5V which is the same as Yuri’s Arduino board.


It does matter what the capacitance (nf, mfd, etc.) is but it isn't critical.  The filtering (noise suppression) increases with increasing capacitance but generally, using a capacitor half the value or twice the value won't make much difference.  As long as the voltage rating exceed the voltage in the circuit, any capacitor will be fine.

Picking the right capacitance is a bit of a shotgun approach anyway, because we really have no idea what the frequency and magitude of the interference is.  Most of the time the interference will be quite small in magnitude and most likely fairly high frequency so it doesen't take a huge capacitance to snub it. Typical capacitances run from .001 to .1 mfd (1 to 100 nf).  I used .05 mfd  in my iGaging because it was the largest value that I had handy.


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## BaronJ (Aug 30, 2018)

Homebrewed,

A linear power supply is called such because it does not use a switching circuit to control the output.  The switching circuit is non linear.
It doesn't matter if the linear power supply is regulated or not.  If it uses a switching circuit to regulate the output then it is not considered linear any more.


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## homebrewed (Aug 30, 2018)

Switcher or linear, they both are a type of regulated suppy and will have negligible droop vs load current when not pushed past their rated output current.  The main thing is to avoid UNregulated supplies so you won't inadvertently damage your DROs or other electronics.


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## BaronJ (Aug 31, 2018)

Hi Homebrewed,

I'm sorry but for accuracy,  A linear power supply does not necessarily have to have a voltage regulator.  They often do, but don't have to.

This is why I posted the warning about using linear power bricks and that the output voltage may be much higher than that marked on the label.
Under the load that they are intended to supply the voltage will be close to the marked voltage.

I do agree with your last comment !
Caveat emptor !  Measure the output voltage before connecting to anything.


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## homebrewed (Aug 31, 2018)

At least we agree on something  Now let's get the folks in Congress in on this!

-H


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