Hi, I'm new here (never used this entire platform before, but as the askElectronics reddit is down I thought i'd follow the trail to lemmy and see what's what). Hopefully this works!...
The standard countryside yokel reply when asked for directions applies, " Arrh, If you need to get to there, I wouldn't be starting from here".
For battery powered LED lighting - you shouldn't be using 12v LED strips. You should be using bare LEDs and a constant current supply. Converting cell voltage to 12v, only to use (probably) resistors to limit LED current isn't the way to go.
You will lose far more, efficiency wise, starting from there, than you are worrying about losing in the series or parallel considerations.
But then, you'd design the required power source and then the charger associated with it - not start with a charger, which then constrains your battery pack topology.
Since I never understood op-amps from reading or practicing problems I wanted to build a circuit to probe around and use different resistor values to set the amplification....
What worked for me, that may not do so for anyone else - is to take an existing circuit (usually a reference one provided by a manufacturer) and build that. Get that working (sometimes, it hasn’t worked- the manufacturer’s technical support department has often been very helpful, especially when their reference design has a design fault or has been misprinted - after doing that, they used to send me unmarked, pre-production chips/etc to play with and provide feedback).
Then modified that design, to test my understanding. Tried different board layouts, guard rings, etc and documented the effect. When it didn’t work as expected - took that back to their tech support to see if we could work out why.
So, for me, taking something that works and keep modifying it, just a little.
I’ve been looking for a simple low-voltage cutoff circuit for a 12v SLA battery, but many of the ones I find have reviews saying that the protection circuit itself drains the battery slowly as well. Is this just inherent in the design, where it has to draw a little to measure the voltage, or are there low-voltage cutoffs that...
You want hysteresis and an energy gap - which means putting energy into the system. You could use a latching relay to minimise insertion loss, however the loss in a conducting MOSFET can be pretty minimal.
SLAs self-discharge, of course.
If the load versus time is predictable, you could use a latching relay and delay voltage checking until the time window for potential cut-off. Or make it entirely period based and not test at all.
It may be that you never need to sense voltage, if your time period between recharging is small enough.
Many operate on that basis - the time interval between recharging may be out of their control (in our case, once, we only had mains electricity between 2am and 4 am each day…) and they provide themselves with enough battery capacity to last that time interval, with a reserve. So no low voltage cut off necessary. So no testing necessary.
The recent post on using a lamp in series to limit potential fault currents has had me thinking about using them as above. Has anyone done this? I can see advantages, cost for one - wirewound resistors can be expensive. Visual indication of a varying load. Make it "short-circuit proof"..
Any particular shunt resistor that you have in mind? You are correct that the lamp brightness would remain the same whilst in the regulated zone. I was more thinking of operation outside that region - eg in a short condition. Having a lamp as the series resistor would reduce the fault current compared to using a fixed resistor.
Not sure what you you mean by “fewer choices of resistance”. The lamp would be the series resistor - other than that, what resistor did you have in mind?
Right to the point: On a BPI-R3, should connecting the UART debug pins directly to the appropriate pins on a DB9 USB serial adapter (rx->tx, tx->rx, gnd->gnd) work? Because I’m just getting a garbled mess in my serial console. I’ve tried all different baud rates. I’m using a high quality serial adapter (Keyspan Tripp...
DuPont connectors equates to logic level signals. There may even be a 3.3 v <>5v link selector on the adapter.
Whereas DB9 equates to "RS232" level signals. Generally, at least the capability to accept those voltage levels, even if not necessarily producing them.
My first step tends to be to connect tx to rx and see if characters typed in a terminal/emulator get echoed.
An RS232 breakout box is pretty much a given necessity, when it comes to sorting out what's happening on all those pins and sorting out what to connect to what.
Hi all! I recently purchased some push-lights for my kitchen from my hardware store, and I stupidly didn’t read the package that said that they shut off after 30 mins. This is super inconvenient in my dark kitchen, and I can’t return them. I figured I might as well tinker with them, and any help would be greatly appreciated....
'fraid that a little bit of effort producing the circuit diagram from the boards is really needed.
I think that it will show what has to be a microcontroller with an input pad going to the switch and another pad going to a base resistor for q1. Q1 switching power to LEDS via RA - D.
The long light looks to be fitted for a an IR receiver. With U1 near it possibly the decoder. As they show the thing stuck on a rafter presumably way out of reach - I suspect that 's a picture from the version with an IR controller. They have produced a cheaper version, without the sensor and re-used the photos.
Now, if that’s how it is - I’d just remove the microcontroller and glue one of my favs upside down on the board and run wires from its pins to the relevant pads (removing the existing microcontroller). I haven’t bought one recently, but 8 pin ones were costing me less than 50p… Having programmed the replacement with an added option to stay on.
I got it with https://sabrent.com/collections/hard-drive-accessories/products/ec-ch2b. But since I bought it in EU, it has that charger. Is there no alternative other than buying a whole new charger?
If you mean a replacement slide-in US standard module - I fear that your chances are slim. I don’t know of a standard that applies to such plates. As it came with a, presumably, external disc drive - asking that manufacturer or its US agent/distributor for help might get something. Even a free replacement power supply. Worth asking, surely?
I don’t recommend using an inline adapter - unless used vertically, the leverage would be too great, unless you added a third leg… You might look for a right angle adapter - that’s the norm in the UK. They can work out well.
Otherwise, you could get an EU socket strip, replacing the plug on the end of its cable with a US one (if it doesn’t actually come with a US plug already).
I’ve got an old oscilloscope and a function generator that I’m trying to use to play around and get more familiar with this kinda stuff. I’m mostly new to electronics (especially analog ones) and I’m having a hard time getting them setup properly....
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?
I'm taking apart a broken tape recorder produced in the 70s (a Tesla B57, made in Czechoslovakia), to harvest some parts (inductors, switches, ...) and maybe reuse the case for some project....
Wear trainers not sling backs. Molten solder and your tootsie don't go well together.
I turn the printed circuit board component side down and wave a hot air gun over the flip side, whilst tapping the board against the edge of work bench. The result is usually a cascade of components (and blobs of molten solder).
Very therapeutic. When I'm stuck trying to work out how to do something, when everything I have tried has failed miserably, I deconstruct something electronic. No, I keep well away from psychiatrists.
You (I anticipate) won't be doing this 9 hours a day, 7 days a week - most of the nasties are long term exposure ones, so a one-off should be fine. If anything ever irritates your eyes or throat, get out of there and ventilate the place.
I'm planning to add a momentary switch to a single loop DC circuit. Will this cause any amount of resistance in the circuit? I'm a complete noobie when it comes to electronics, any resource links or clarification is appreciated. I know the type of material/width of wire and a pot will cause resistance but will any component put...
That is pretty much exactly a conventional momentary switch. It just happens to be packaged for use controlling something a little different.
It should be fine for your application.
One thing to note - the contacts will probably "bounce" as the switch is closed. Produce a string of momentary connections and disconnections for, oh, say the first few thousandths of a second. That's perfectly normal for a mechanical switch.
That won't matter in its intended application. But if you are using it with electronics, say counting the number of times the switch is operated - the results can be unexpected.
You can look up "debounce" to see how this can be worked-around.
Hello. I'm a hobbist on electronics repairs, and I did some repairs on stuff powered from the wall socket before, using a serial bulb to protect the circuit in case there's a short. Now I want to troubleshoot a board that works at 3V and very low current (like no more than 100mA). So, how can I properly size the bulb I need for...
You can make your own current-limited power supply, probably from bits and pieces you already have. Let's say that you have a 5v dc power supply and a hand full of rectifier diodes and resistors (various values and sizes).
Put a series chain of forward biased rectifier diodes and resistor(s) across your 6v supply. Choose enough diodes to give you a 3v output. Now choose a combination of series/parallel resistors to give you a 2v drop with a current of, say 100mA. You need 20 ohms - so that could be 5 x 100 ohm resistors in parallel.
The most current that can put out is the full 5v across 20 ohms - but at that point the output voltage will be near zero.
Bench supplies, well reasonable ones, allow you to set a current limit as well as an output voltage. At loads below that current limit - it operates as a constant voltage supply. At loads above - it operates as a "constant current" supply. You would set the output current limit to 100mA and that's the most that it will output.
Now the rectifier diodes plus resistor would allow the current to increase above 100mA, up to 250mA when the output voltage will be near zero (short circuited) - if you want better than that, then you can add a transistor and a few other components.
boosted 18650 circuit - parallel or series? Or doesn't matter?
Hi, I'm new here (never used this entire platform before, but as the askElectronics reddit is down I thought i'd follow the trail to lemmy and see what's what). Hopefully this works!...
Non-Inverting LM358 Circuit Not Working (discuss.tchncs.de)
Since I never understood op-amps from reading or practicing problems I wanted to build a circuit to probe around and use different resistor values to set the amplification....
Can anyone here recommend a good, simple 12v low-voltage cutoff?
I’ve been looking for a simple low-voltage cutoff circuit for a 12v SLA battery, but many of the ones I find have reviews saying that the protection circuit itself drains the battery slowly as well. Is this just inherent in the design, where it has to draw a little to measure the voltage, or are there low-voltage cutoffs that...
deleted_by_moderator
Is this one-piece battery-to-PCB "clip" standard (for easy replacement) or a custom piece? +PCB pad ? (discuss.tchncs.de)
Hello,...
Using an incandescent lamp as the "resistor" for a zener/avalanche diode regulated supply
The recent post on using a lamp in series to limit potential fault currents has had me thinking about using them as above. Has anyone done this? I can see advantages, cost for one - wirewound resistors can be expensive. Visual indication of a varying load. Make it "short-circuit proof"..
Using multiple windings on two transformers to create one output at maximum power
Hi everyone, I’ve just resurrected a broken Weller TCP1 and need a 24v ac supply for it....
SBC UART debug troubleshooting
Right to the point: On a BPI-R3, should connecting the UART debug pins directly to the appropriate pins on a DB9 USB serial adapter (rx->tx, tx->rx, gnd->gnd) work? Because I’m just getting a garbled mess in my serial console. I’ve tried all different baud rates. I’m using a high quality serial adapter (Keyspan Tripp...
Help Bypassing Timer on LED Lights
Hi all! I recently purchased some push-lights for my kitchen from my hardware store, and I stupidly didn’t read the package that said that they shut off after 30 mins. This is super inconvenient in my dark kitchen, and I can’t return them. I figured I might as well tinker with them, and any help would be greatly appreciated....
Can I get a North American plug for this 36W DC charger? (kbin.social)
I got it with https://sabrent.com/collections/hard-drive-accessories/products/ec-ch2b. But since I bought it in EU, it has that charger. Is there no alternative other than buying a whole new charger?
How to setup this function generator with this oscilloscope? (imgur.com)
I’ve got an old oscilloscope and a function generator that I’m trying to use to play around and get more familiar with this kinda stuff. I’m mostly new to electronics (especially analog ones) and I’m having a hard time getting them setup properly....
Safety tips when disassembling old electronics?
I'm taking apart a broken tape recorder produced in the 70s (a Tesla B57, made in Czechoslovakia), to harvest some parts (inductors, switches, ...) and maybe reuse the case for some project....
What creates resistance in a circuit?
I'm planning to add a momentary switch to a single loop DC circuit. Will this cause any amount of resistance in the circuit? I'm a complete noobie when it comes to electronics, any resource links or clarification is appreciated. I know the type of material/width of wire and a pot will cause resistance but will any component put...
How to properly size a serial bulb for protection when troubleshooting a circuit?
Hello. I'm a hobbist on electronics repairs, and I did some repairs on stuff powered from the wall socket before, using a serial bulb to protect the circuit in case there's a short. Now I want to troubleshoot a board that works at 3V and very low current (like no more than 100mA). So, how can I properly size the bulb I need for...