Needing more than a spark test?

[graham-xrf]

I too have been mulling over the function of the silver foil. I don't think it is used to increase the x-ray flux because the maximum energy from the x-ray tube is only high enough to get one 22Kev photon from an incident 40Kev photon. It _might_ be used to reduce the energy of the photons hitting the sample, to avoid exciting other transitions that would muddy the water, so to speak, but that is pure speculation on my part.

Yes - exactly as I said, simply because any silver output needs more than half the 40kV.

Do you have a slightly bigger image, or something that I may include a Teensy preferred interface pinout?

 

[homebrewed]

has ordered one with the difficult surface mount assembly already done.

I guess it depends on one's ability to hand-solder a 48LQFP. I wouldn't have gone with the price JLC wanted for the ADC -- it was about 2X the Digikey price-- had they had it in stock. Hand soldering LQFP's is a lot easier if you apply solder flux first, it helps keep the solder confined to the lead you're soldering down. You actually can pre-tin the PCB footprint w/o problems if you put solder flux down first.

I haven't used solder paste because I don't have a good way to apply it. However, in the case where you already have most components soldered down (including some on the back of the PCB), I think that hand soldering probably is the best way to go.

 

[graham-xrf]

I guess it depends on one's ability to hand-solder a 48LQFP. I wouldn't have gone with the price JLC wanted for the ADC -- it was about 2X the Digikey price-- had they had it in stock. Hand soldering LQFP's is a lot easier if you apply solder flux first, it helps keep the solder confined to the lead you're soldering down. You actually can pre-tin the PCB footprint w/o problems if you put solder flux down first.

I haven't used solder paste because I don't have a good way to apply it. However, in the case where you already have most components soldered down (including some on the back of the PCB), I think that hand soldering probably is the best way to go.

Given the design convergence, but the very different physical mounting of the PIN diode between concepts, I had in mind to get a first PCB in step-and repeat with as many as I could fit on the standard area board, and also to make circuit options up to the ADC as experimenter-friendly as possible. Also, I want, as much as possible, to simply follow, and include interface to Teensy as you might prefer. I know I will probably have some collateral damage on the way, and I may well be picking on your experience in re-flow soldering these things.

Once I have the KiCad layout, even though it be a bit of a prototype, I should have enough spare PCBs to distribute to the few here who are interested, and might want to play. My scheme uses a little separate PCB to mount the PIN diode, but I can include a link-able option to mount one direct on the mother PCB.

 

[WobblyHand]

If you don't have a stencil and a way to apply solder paste, you can use solder paste in a syringe with a small bore needle. I have been able to solder DFN8 devices that way as well as larger devices. Using the syringe under the microscope I can apply the paste to the tiny pads with some effort. A stencil is a heck of a lot easier!

 

[rwm]

Please take pics of your soldering process.
Hey can someone review why this device will be superior to the Theremino project? What are we improving on?

I just realized that if we get bored with 59 KeV we may have other options to see heavier elements.
I am not sure if these have enough activity but multiple sources and longer acquisition times?

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[homebrewed]

Do you have a slightly bigger image, or something that I may include a Teensy preferred interface pinout?

Are you talking about making something like an ADC shield? Funny you should bring that up, I was thinking about that last night.

I've attached a PDF version of the current layout, with top metal, silkscreen and the ground plane. This is the design that's being fabbed and stuffed. The board dimensions are 75 x 35.2mm. I moved the two 8-pin headers to accommodate the mounting holes: but if it's turned into a shield it won't need mounting holes.

Right now I don't know if it would be possible to have a pinout that's compatible with both T4.0 _and_ 4.1. I now have one of each with the product card so it won't be too difficult to check that.

BTW it appears that EasyEDA has PCB footprints for both the T4.0 and 4.1. An adapter board is certainly possible but it would be best if we could avoid that. A complicating factor is that the choice(s) available for 8/16 parallel input pins are fixed so there's no wiggle room there. The control pins are a different story.

 

[WobblyHand]

Please take pics of your soldering process.

If addressed to me, for one offs, I have a 15gm syringe with solder paste in it. There's a 26 or 28 awg needle on it. I just squeeze out the paste on to individual pads, place the part and use a hot air gun. There's no way to take a picture, because my hands are full!

This is not practical for most boards. For them, I'd get a stencil made and squeegee the paste on, place the parts and put it in a dedicated toaster oven to reflow, if I were to do it at home.

 

[homebrewed]

Please take pics of your soldering process.
Hey can someone review why this device will be superior to the Theremino project? What are we improving on?

I think the final system will be designed to be portable. My current approach is NOT portable but that was a deliberate decision, to avoid the additional complication(s) involved. For instance, I'm using bench supplies and all the different parts are strung out on the bench. To make an analogy, it makes no sense (to me anyway) to work on the body color when we don't know what shape the automobile is going to have.

 

[WobblyHand]

Are you talking about making something like an ADC shield? Funny you should bring that up, I was thinking about that last night.

I've attached a PDF version of the current layout, with top metal, silkscreen and the ground plane. This is the design that's being fabbed and stuffed. The board dimensions are 75 x 35.2mm. I moved the two 8-pin headers to accommodate the mounting holes: but if it's turned into a shield it won't need mounting holes.

Right now I don't know if it would be possible to have a pinout that's compatible with both T4.0 _and_ 4.1. I now have one of each with the product card so it won't be too difficult to check that.

BTW it appears that EasyEDA has PCB footprints for both the T4.0 and 4.1. An adapter board is certainly possible but it would be best if we could avoid that. A complicating factor is that the choice(s) available for 8/16 parallel input pins are fixed so there's no wiggle room there. The control pins are a different story.

I have a KiCAD T4.1 footprint that I used successfully on my ELS board. Let me dig it up. I found the zip file with all the Teensy's. It's 6MB, hope it goes through.

 

[homebrewed]

If addressed to me, for one offs, I have a 15gm syringe with solder paste in it. There's a 26 or 28 awg needle on it. I just squeeze out the paste on to individual pads, place the part and use a hot air gun. There's no way to take a picture, because my hands are full!

This is not practical for most boards. For them, I'd get a stencil made and squeegee the paste on, place the parts and put it in a dedicated toaster oven to reflow, if I were to do it at home.

Folks that have a 3D printer can make a stencil holder which aligns the stencil with the PCB. I have a friend that's doing his own boards that way.

Many PCB fab houses will make stencils along with the board, for a relatively small additional fee.

BTW the board I'm getting done does have some hand-soldering for a slightly higher cost. Probably because the design has two capacitors on the back of the board.