PS For future reference, does this sort of exposed PCB trace (pad?) used for electrical connection take solder well?
I can’t tell if you have gold plate or just raw copper (probably gold. But in either case, yes, it is solderable. You can think a little bit about how they manufacture the boards. First the print on the green solder resist, then they dunk it into an electroplating bath for a gold finish, or a dunk it in solder for HASL. It would be a lot of trouble to go through (=$$$) to individually mask off that part of the board for some special process.
Second picture: To me looks like Q1 (3400) is an NMOS which connects the LEDs to power. The ‘gate’ is marked yellow. It is the ‘control’ input of the MOSFET. The 4 resistors RD RC RB RA (purple) probably limit the current through the LEDs. If you’re lucky, then an easy hack would be to bypass this transistor: Remove Q1 and connect the red and green marks via a mechanical switch. You’d need to scratch away the white coating until you get copper. Then solder wires there. As a consistency check you could measure the voltage over Q1 (red and green marks). Measure once when the module is plugged in but switched off, and once when the LEDs light up. If you see a voltage while the LEDs are dark, then this would partially confirm my guess. As a test: Before removing Q1 you could also try to bypass Q1 with a resistor (~ one, two kOhm) while the LEDs are off. If you see LEDs now lighting dimm, you know that Q1 is the one switching the LEDs.
Other possibility: It might possible that the timeout is computed with an R-C circuit. for 30min you need a rather large resistor because there can’t be very big transistors. R1 (blue) is the largest one. Experiment could be to remove it and see if timeout is still 30min. Or put another 10k resistor in series and see if the timeout gets shorter.
Wondering: What voltage do you connect to the module? Please be extra careful if you have somewhere mains supply voltage.
We have a council-supported “man cave” - with a couple of funded workshop technicians and lots of unpaid volunteer specialist engineers, mechanics, DIY’ers etc. Plus a very well equipped multi-discipline workshop. So you could take those bits of kit there and someone would give you a hand setting them up, teaching you how to use them, repairing them/maintaining them as needed. Even getting them calibration certificates (thanks to one of the volunteers who has access to calibration equipment). If you don’t have one locally - wouldn’t the technician at a local school/college/university help? Is there a local community online group that you could join and ask for help?
Yes you can absolutely breadboard it. Forcing a current is as easy as following ohm’s law. Make sure there is a certain voltage across a resistor and ensure that only a negligible amount of that current is leaked elsewhere. A difference amplifier is a good way to ensure this, as long as you pay attention to the amplifier input currents.
If current regulation isn’t super important, a highish voltage (say 24+ V) and a large resistor will also work because the variation of threshold voltage will be so small that the voltage across the resistor will be relatively stable.
I think there is some confusion about the word diode here. The transistor is effectively an inverting amplifier, that is that the drain voltage is reduced if the gate voltage is increased. By tying them together, they reach a stable configuration where the gate is just high enough to make the drain low enough for them to be equal. In this configuration, there are two terminals, hence the di in diode. Like a traditional diode, it has a very nonlinear voltage-current relationship. If you apply 10V to it, theoretically the current would be thousands of amperes. Practically that won’t happen but you will blow up the transistor.
I don’t know enough about radiation and semiconductor physics to answer your other questions but if I were you I would just build it and test it. MOSFETs and resistors are cheap and if you do have a radiating source on hand it might be easier to try and fail than to hope someone here can tell you what your part will do when exposed to conditions outside of the manufacturer recommendations.
Searching for the number hasn't gotten me anywhere neither has searching by the dimensions of the jack. Would like to avoid stealing parts off other systems but as a last resort would consider it.
Thank you for the reply. The one we have on hand has 4 pins. An exact replacement would be great, but at this point if we can just get one to work, that'd be fine as well. I appreciate the help! I'll dig around and see if I can track down datasheets to review.
I've successfully used incandescent Bulbs in the past. They have barely any resistance when cold, which is the reason why they usually blow up when you turn them on.
For their size, usually I use more than the power the device will use but less than the wires can handle for a while. In your case id get a lamp with a E10 socket, for example 3.5V 0,7W.
Alternatively you can use a PSU with current limiting features.
You could try connecting a current source to the source of the FET, connect the gate to a voltage reference, and connect the drain to a supply. Then the gate source voltage will be kept at threshold at all times and can be measured with a difference amplifier.
This could be done with a couple of op-amps provided they aren't adversely affected by the radiation.
https://sensepeek.com/ do manufactur those nice PCBite SP10 probes. New improved series: SQ10 probes. They also have 500MHz Oscilloscope probes! They are awesome :D
The SensePeek PCBite system is really nice. They're the best board holders I've ever used, very stable. Great for testing, and great for soldering. The probes are ridiculously helpful, it's downright easy to probe adjacent pins on a 0.5mm pitch QFP (with some magnification)! All rather expensive, but very, very worth it for the time saved.
Maybe you can use this to find more connectors that could match yours: connectorbook.com/identification.html?m=NT&n=lo_p…It has a pretty handy identification tool (you can even browse by pictures). It usually suggests quite an amount of connectors but it can guide you in the right direction and you can look at the according datasheets to find out more. By the way the creator of this community made that homepage and a book related to it (or probably the other way round 😅).
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