# VFD control panel



## Eremius (Feb 10, 2014)

I believe I have gotten all of the parts I need to create this but I do have a couple of clarification questions.

On this item, the magnet they provide looks like it won't work well with my Atlas lathe.  Can I just get a small rare earth magnet which I can install behind the gear on the far left of the spindle (bull gear?)?  I am assuming it just detects a magnetic field, it really doesn't care what provides it.

Second, I am going to be using a modified PC power supply to power the tach with 10v DC.  I would like to run a relay to shut that power supply off when the lathe is not running.  I know enough to know generally what I need but I would appreciate a suggestion as to an inexpensive relay for cutting the power when the switch is turned off.

Thanks in advance for any suggestions.


----------



## Hawkeye (Feb 11, 2014)

You're right about the hall sensor not caring what type of magnet provides the trigger. I use rare earth magnets on all of my tachometers.

If you're switching your low voltage power supply, do it on the high voltage side. PC power supplies, at least the older ones, shouldn't be powered up if there is no load connected. Tends to kill the output transistors.

Any relay with a 110 VAC coil should work to switch your 10 volt supply. PCB-mount types will be cheaper than socket-mounted relays. Solder the wires onto the legs of the relay and seal them with heat-shrink tubing.


----------



## Eremius (Feb 11, 2014)

So something like this would be appropriate?

- - - Updated - - -



Hawkeye said:


> If you're switching your low voltage power supply, do it on the high voltage side. PC power supplies, at least the older ones, shouldn't be powered up if there is no load connected. Tends to kill the output transistors.



Following this guide, there is a resistor built in so there is always a load.  Where would we be without the internet. )


----------



## Hawkeye (Feb 11, 2014)

Absolutely. I converted a switching power supply to use as a camera supply. I added a 1k resistor as a safety load. It 'wasted' all of 6 mA.


----------



## Eremius (Feb 11, 2014)

I have done a little reading and my VFD provides 10v for it's "accessory" connections.  It looks like the relay wants 12v, will I have an issue with that?


----------



## DMS (Feb 11, 2014)

Another option would be to use the "Power ON" pin. This is the green wire in the bundle of wires that is part of the large "ATX" power connector.

http://en.wikipedia.org/wiki/ATX

All you need to do is to short this to ground (Power supply ground). This could be done through a small relay.

Do be careful of that 10v output, they are typically only rated for a few tens of milliamps.


----------



## rdhem2 (Feb 12, 2014)

*Do be careful of that 10v output, they are typically only rated for a few tens of milliamps.[/QUOTE]*

Mr. DMS is so right on.  These sources seem to be more for a reference point rather then a source of power to operate something.

I would go with your earlier thinking and use a separate source power supply.  That has worked best for me.


----------

