The diodes at least provide some steps - which just LEDs and resistors don’t. The dissipation in the main series resistors will be quite something, also. (You will probably need several resistors in series, if you use standard ones, with their standard voltage limits).
The smd codes kind of suck. They’re used on devices where there isn’t room for the full PN. But they’re not standardized well. Are often unique per footprint, but even then, not a guarantee.
I looked up “CAZ” here: smd.yooneed.one/code4341.html and found a part that matches the footprint. Then googled around and found the LN61CC3002MR-G on lcsc.
It can be very hard to find a part on Google, or say Digikey, if it’s made by a Chinese company. LCSC can be helpful since they’re based in China.
usually fans have a min start voltage. u can try if your fan starts at 5v and if the resulting RPM is ok for you, just solder it without any resistor on USB
I’m old school. I’d reverse engineer that part of the board, work out what the resistor was doing and then choose a value, much as the original designer did.
From that small section of the board - I’d guess that it is a resistor in the CR voltage dropper, used to power the electronics.
...but how in the world do you burn a 1 GΩ resistor? That looks sort of like it could be a 1 watt resistor too. So back-of-the-napkin this would have to be from over a 30kV supply. So that sounds a bit off.
Unless it isn't. One hell of a bread maker then. I want one.
Only thing I can think of, maybe it’s a bleeder resistor for that cap, and it failed by some kind of internal short which reduced its resistance (and increased its heat dissipation hence the blackened board)? But fails-short is an unusual failure mode for a resistor and 1 GΩ is pretty high even for a bleeder, so maybe we’re misreading something.
Usual situation - if I needed to interface to 5 cameras I wouldn’t start with ones that needed: “The DVP physical interface consists of a single, 100-conductor, 110-ohm cable organized. as 45 differential signal pairs. These signal pairs consist of the following: • 36 RGB data pairs. • 2 clock pairs.” So, you would be interfacing to 5 x 45 differential pairs. I’d be looking for camera modules with serial output…
Or, as you suggest, give each camera something that can convert that lot into a single serial data stream. Or even process it down to a QR code and just send that. Or even do what-ever it is that you want to do with that code, once received.
Connecting each camera to its own ESP32, which process the data and sends only necessary information to the main ESP32, I think is a cool idea.
I plan to use this Schamatic as a guide for building the ESP32 cam parts on my pcb, although I’m sure I’ll be using a slightly newer ESP32: github.com/SeeedDocument/…/ESP32_CAM_V1.6.pdf
It seems that the PINS U0TXD and U0RXD are free. Can I use these to connect them to the main ESP32 via UART or is there a better way to connect all ESP32 cams to the main ESP32?
And there is one more question. How can I program the ESP32 of the cams? The main ESP32 will be connected to a Micro-B SMD USB connector. Do I need another one for each ESP32 (for the cams) or is it possible to program all ESP32 via the same USB connector?
Depends on your programming abilities. You can set up a “1-Wire” bus and put the lot on that. You could have one microcontroller as master and the rest as slaves - your external USB connection would go to the master and it could, in theory at least, then pass on program upgrades to the others. Clearly they would all have to be programmed individually, originally. But, quite frankly, the investment in time and effort on setting all that up? If you had dozens, hundreds - then yes. But you only have a small hand full. I’d just bring out their USB connections and program them individually, via those. I think each one has a unique identifier, stored in ROM - so they could all run the same software and include that identifier in messages on the bus.
I’m puzzled - you describe wanting to add a headphone jack (eg an output jack socket into which headphones can be plugged) - yet you seem to actually want a socket that provides auxiliary input.
However, if you are indeed trying to add external input and are disconnecting the inputs to an amplifier - you might want to tie those disconnected inputs to ground.
My bad - yes I mean an AUX input I thought I would’ve needed to ground the unused lines (not sure if I should connect to ground directly or with a resistor) - you think that could be the cause of the whine? The whine comes from the front speakers too. And I really can’t understand how and why I can still get some signal from the stereo…
It’s usually a good idea to look at what’s normally connected, when breaking a circuit, and replicate that. Which I seem to remember is a 10k resistor with a parallel capacitor (being too lazy to go back and look again). You could try the same combination, in place of the added input cable, on the lines that you plan to use and see if it whines. If not, add the cable(s) and try again. That may stop it happening on all channels.
There are two muting methods - open circuit the input (via a switch or a gate) - in which case there will probably still be some signal transfer through capacitive coupling - especially if the amp side of the open circuit is high gain. Or short the signal path to ground - and that short will have some impedance and thus the signal is only attenuated and not removed all together.
Turning the amp gain to far higher than it ever would be in practice is hardly a fair test. There aren’t many amps that will be noise free under those conditions - and, in this case, there will be a signal to amplify, albeit highly attenuated.
It’s good to be cautious - cascade failure can be waiting to bite. Never direct connect unless unavoidable - add a series capacitor, if you can. Yes, not usually a good idea to provide a dc path unless essential and, even then, current limit it if possible.
It’s usually a good idea to look at what’s normally connected, when breaking a circuit, and replicate that. Which I seem to remember is a 10k resistor with a parallel capacitor (being too lazy to go back and look again).
There’s a resistor, then parallel capacitor and resistor to ground, and finally a capacitor to the amp. I could try replicating the parallel pair if that could help
add a series capacitor, if you can.
Would that be a polarised capacitor for protection? And on both the original and my added lines?
You measured the resistor at 403 Ohms? That would qualify it as “not failed” then. Resistors pretty much exclusively fail open, or on rare occasions, out-of-tolerance on the high side. After 5 years of doing electronics diagnostics for USAF aircraft, I never say any other type of resistor failures.
Brilliant! Thanks you so much for taking the time and effort to help me with this - and for mentioning “CONNECTORBOOK.COM” so I can add that as a useful reference. Not a chassis mount but that always was a mission impossible to find, I suspect.
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