So I checked my supply voltages, and that opened an unexpected can of worms. The PIR sensor has it's own onboard linear regulator, and it's pumping-out the expected 3.3VDC. The weird thing is the main 5V supply was only putting out 3.8V. Despite that, the Raspberry Pi also had the correct internal 3.3V supply (it also has it's own onboard supply).
So, the first mystery is why a DCDC converter rated for 1amp, and typically supplying 400mA conked-out when it's not getting warm or overloaded. I confirmed the RasPi typically uses around 200mA, and occasionally peaks around 280mA. I have to dig further into the regulators on the RasPi and PIR sensor to understand why they still produce 3.3V when their input is way-below 5.0VDC. I'm glad that they do, but I want to confirm why. I'll see what I have laying around for replacing the 5V DCDC converter, and if they beefier ones I have will fit on the PCB. Once I get this thing back together, I'll see if the PIR sensor is back to normal. I have some replacement PIR sensors on the way. Why the DCDC converter failed is another mystery; I use these on all my projects, and seeing one fail is disturbing, especially because many of my gizmos dont have onboard A/D converters to monitor the power supplies. On Thursday, November 21, 2024 at 5:08:19 PM UTC-8 Max Di Noi wrote: > I had that problem once and it was due to a faulty capacitor on the high > voltage power supply creating instability on the HV circuitry and affecting > the PIR circuitry, which was odd as that itself had its own capacitors > located close to the chip and the main power supply had plenty of > stabilised power. > > Now I'm trying to stabilise a microwave motion sensor that I designed > based on one of those commercially available. It's embedded in the pcb, > works OK but I need to figure out how to calibrate it more easily. It > depends on temperature and material of the pcb. I purchased a frequency > receiver up to 6gHz and I can see the signal on the screen. So that's a > good start! Sorry, got sidetracked, slightly off topic :-) > > -------- Original message -------- > From: newxito <[email protected]> > Date: 21/11/2024 17:04 (GMT+00:00) > To: neonixie-l <[email protected]> > Subject: [neonixie-l] Re: PIR sensor got very sensitive > > Maybe you have to clean the trimmer resistors or there is a little bug > inside, I had that problem but it was with an outside PIR :-) > > gregebert schrieb am Donnerstag, 21. November 2024 um 07:50:38 UTC+1: > >> Here's a strange story....a few weeks ago, I noticed my 7971 clock was >> running a lot more than it was a few years ago. After some experimenting, I >> found out the PIR sensor is getting a lot of false triggers (no movement in >> room, even covering-up the sensor didn't keep it off). Turning-back the >> sensitivity 1/4 turn did nothing, so I put it at minimum sensitivity and it >> seems to stop the false triggering. It still detects motion. >> >> Anyone else see this happen ? The sensor has been in-use for about 6 >> years; it's one of those cheap 5V units that cost about 1 USD and worked >> fine for many years. >> >> >> -- > You received this message because you are subscribed to the Google Groups > "neonixie-l" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion, visit > https://groups.google.com/d/msgid/neonixie-l/f054d906-771b-4e73-9593-53c3e95e56f5n%40googlegroups.com > > <https://groups.google.com/d/msgid/neonixie-l/f054d906-771b-4e73-9593-53c3e95e56f5n%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion, visit https://groups.google.com/d/msgid/neonixie-l/340ffb9a-b775-4a49-b1ae-0fde15e3ac6bn%40googlegroups.com.
