# Making a test panel for multiple circuits

Discussion in 'The Projects Forum' started by vladthegreat1, Aug 13, 2015.

Dec 26, 2014
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Hey everyone so I have acquired 1000 units of a unique led circuit and I need a way to test a bunch of them at once. They run off of a 12 volt source and each led is 30mA and there are 2 on each unit. So how would I go about making a test bench circuit? My power supply can provide up to 30v and 3 amps . Does this mean I can run 30 units in parallel from this power supply. Basically I want to be able to plug as many units as possible into this test bench (the one I'm trying to figure out how to make)and press a switch and all LED pcbs power on. Please help. Thank you kindly.

2. ### absf Senior Member

Dec 29, 2010
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What functionality are there in your unique circuit boards besides providing power? DO you need to press a certain button/buttons or provide signals to the board?

Does the board has some kind of jack or connectors? If none of all these, you could just solder 10 or 20 pairs of crocodile clips and clip them to the power input pins and just test them manually. After completing one batch, just move on to the next 10/20 boards swapping the c. clips.

Allen

Dec 26, 2014
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There doesn't have to be buttons. Each pcb has a male connector and I have the female end of that connector that is not going to be used so I figured I'd put them on a custom pcb that I can make if I had the correct circuit . Power would be applied to the test circuit and all 10-20 pcbs would receive 12volts am I correct in that thinking?

Fyi each pcb is like this: (r1 and 2 are resistors)
(Pos)--(led1)--(r1)--(r2)--(led2)--(neg)

Hope u can understand this text circuit drawing. I don't know why this pcb was designed that way with 2 resistors like that but it was and it works. Each resistor is 150ohms each led has a voltage drop of about 3.5

Dec 26, 2014
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I am in bed using my phone I found a cool app that let me generate a circuit and test it.hopefully this picture Will show u. Interesting enough the app shows this circuit working..

• ###### %22Pcb test circuit.png
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78.5 KB
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Dec 26, 2014
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So does anyone know if this is feasible?if I connect up the pcbs like the diagram and set the proper current I should be able to run everything fine without burning anything up?

6. ### pwdixon Member

Oct 11, 2012
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If your PSU is capable of 3A then you could connect 100 LEDs at 30mA each.

7. ### ErnieM AAC Fanatic!

Apr 24, 2011
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OK Vlad, the one thing you did not define is "test."

What does test mean? Will lighting them up be sufficient? Do you care what current they take? If you bang 30 together on your test stand and one is shorted will you be able to find that? What is this connector, will you be using (and this testing) that too? Why a PCB for test?

8. ### eetech00 Active Member

Jun 8, 2013
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ErnieM is right.

What tests are required to determine if a unit has passed or failed?
How will those tests be performed?
What failure modes do you anticipate? And how can you protect your test bed from potential damage?

Dec 26, 2014
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Test simply means i will be checking to see that the LEDs on the PCB light up. So during my testing i plan to write a letter to notify this on the PCB with a sharpie) and to provide 12 volts of power to each PCB at once to power them up. each PCB requires 12V to be powered at full brightness.
i have 1000 units and would like to to be able to plug them in 10-30 at a time test them than do another batch.
If i test 30 of them out the one that will not be working will be the one not lighting up due to parallel circuit. (if one of the leds on the pcb does not light that will effect the other once since the led circuit is series. but that just means to me that the pcb is a failure and i set it aside) the connector is a simple 2 prong socket and plug. it just allows for plug and play rather than the wires being soldered directly to the source... should it need to be replaced just unplug and plug in a new one.

The reason i wanted to create a PCB is because i only have 1000 pcbs but in the near future (in a few months) i will probably be acquiring more and more. but moreso, i have the method of making pcb (laminator, solder mask, etchant, tinning solution, and i have quite a few left over FR4 boards that i could use) and would like to utilize it.

Dec 26, 2014
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The tests determined pass or fail will be:

Power PCB 12V
PCB leds on: Pass
PCB leds off: fail

If a unit fails i toss it into the bad pile. that is all.

As far as protecting the test bed this is why i have come on here i want to be sure i make the bed and power it properly to omit failure.

In PDWixons reply he says if I have PSU capable of 3amp 12v it should work. But i just want to make doubly sure that if say for whatever reason i were only to plug in 15 of the 30 PCBs into the test panel.... would that mean 15 of the PCB's would be receiving double the current? and even if they were gettting double the current at the Connector wouldnt the PCBS themselves already be protected since they contain resistors in their circuitry?

Dec 26, 2014
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Dec 26, 2014
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I have a visual for you folks that have been great in answering me

13. ### absf Senior Member

Dec 29, 2010
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Now I see what you need. Your circuit board is wired to a so called "JST" type of female plug. You just have to make a PCB with 30 JST male socket with a fuse connected to every 4 sockets like this ---

The JST male and female socket is available in several sizes - some are 2.5mm, 1.25mm and 2mm pitches. So make sure the size of the plug and buy the corresponding matching sockets. Like this one here....

http://www.ebay.com/itm/20-SETS-Mic...ires-Cables-/161717777439?hash=item25a721741f

Allen