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  1. KrisBlueNZ

    Help identifying transformer

    Hi Dan and welcome to Electronics Point :-) I don't think there's anything wrong with that transformer. It looks like the circuit board has burnt up somehow, and deposited some black gunk on the wires on the underside of the transformer. The wire isn't damaged and show no signs of overheating...
  2. KrisBlueNZ

    Beginner circuit question - 555 timer

    Hi Dave and welcome to Electronics Point :-) You have the right idea, but as Bluejets pointed out, five minutes is too long for a resistor-capacitor delay. There are other ways to do it though. A common one is to use the CD4060 (see...
  3. KrisBlueNZ

    Is this switch safe? Dual 26650

    Mistakenly? You're being very generous there Hop. The 60A claim, in conjunction with the high price (many times higher than the same switch from different suppliers) and the absence of any mention of the current rating in the body of the ad, suggests to me that the seller is being deliberately...
  4. KrisBlueNZ

    Is this switch safe? Dual 26650

    Current would be (3.6 + 3.0 + 3.0 + 3.0) / 1000 = 12.6 mA. CR2032 capacity around 150 mAh; total run time 150 / 12.6 = 12 hours Hit duration 2 seconds; number of hits would be (12 × 60 × 60) / 2 = 21,600 hits. That's just for the CR2032 cells. Obviously you'll need to recharge the main cells a...
  5. KrisBlueNZ

    Stage Line 500W amp repair project

    Hi again. Sorry for the delay. Yes, those pictures are very good, thanks. I'm asking a lot of questions in this post. Can you go through it point by point and respond to all of them please. When you said in post #18 that you had accidentally connected positive and negative voltages backwards...
  6. KrisBlueNZ

    Is this switch safe? Dual 26650

    No objections. It looks nice! If the specs are real, yes you could avoid the MOSFET and the 9V battery for the gate supply voltage. But it looks just like the 3A one apart from the colour of the plastic, and as you say, with no manufacturers' reference, it could very well be bogus. Digi-Key...
  7. KrisBlueNZ

    Project Logs

    That was quick! It looks really good Ian :-) I especially like the image gallery feature.
  8. Fanrunon - delayed turn-off for bathroom extractor fan

    Fanrunon - delayed turn-off for bathroom extractor fan

    My 'Fanrunon' project is a turn-off delay timer module for use with an AC mains load such as a fan or a light. The rated maximum current is 2.5A RMS. It uses a triac for switching, and a Microchip PIC12F675 microcontroller. At this time, I have not built up the hardware, and I have only partly...
  9. KrisBlueNZ

    Fanrunon - delayed turn-off for bathroom extractor fan

    KrisBlueNZ submitted a new Showcase Item: Fanrunon - delayed turn-off for bathroom extractor fan Read more about this showcase item here...
  10. KrisBlueNZ

    solar phone charger

    It's nice to imagine that you can just stick a solar panel on the back of your phone and leave it in the sun for a while to charge, but it's nowhere near workable. According to its specification, that panel can deliver about 100 mW. That's about 1/50th of a typical USB charger. So if your phone...
  11. KrisBlueNZ

    Arghhh! I Hate RS232 :)

    Thanks guys. I think the first mistake was me saying "but thanks for playing" to pebe. I said it because I thought that it was obvious that an RS-232 transceiver was needed, and I assumed that pebe must have recommended an RS-485 device thinking that it was RS-232. That comment was unnecessary...
  12. KrisBlueNZ

    AC power generation and transformers

    At the company I used to work for, we would sometimes get sent out onsite with power company electricians, and I've heard a few good stories, like the time an air break switch started to open (or close; not sure which) on a live line! The linesman's advice is "if you see me cover my ears and...
  13. KrisBlueNZ

    MOSFETs that make you scratch your head..

    No... I presume you to be infallible! How much does it affect the outcome?
  14. KrisBlueNZ

    Is this switch safe? Dual 26650

    Bluejets, are you sure that's the right switch? I don't see a part number mentioned anywhere in this thread. Levitys: No problem :-) If Bluejets has the right switch in post #10, it's designed to have a 12V DC supply for the illumination. You might be able to make it illuminate properly at a...
  15. KrisBlueNZ

    I need to time an AC outlet by seconds, or a break in a DC line

    "If all you have is a hammer, everything looks like a nail" (Not exactly relevant, but I like it.) :-)
  16. KrisBlueNZ

    solar phone charger

    Assuming the solar panel is producing full power (very unlikely), assuming that the 1.5W specification is real and not just a marketing "exaggeration" (i.e. a lie), and assuming 100% efficiency in the converter (it's usually around 80%), your maximum output current at 5V will be 300 mA. (I = P /...
  17. KrisBlueNZ

    MOSFETs that make you scratch your head..

    Thanks for doing the calcs Steve :-) With a drain current of 4A the ON-resistance at VGS = 5V won't be a problem either.
  18. KrisBlueNZ

    Need Some Help Figuring Out How to Use the PDSP2112

    No problem!
  19. KrisBlueNZ

    FM modulator light only and no transmitting

    Here's the power supply with the diode added. This circuit has an output of about 5V. If your FM transmitter circuit needs a different voltage, you'll need to change D1 to a zener diode with a different voltage - its zener voltage should be about 0.6~0.7V higher than the output voltage you want...
  20. KrisBlueNZ

    Choke for a NC motion sensor on a NO system

    Harald's circuit in post #6 is a very good answer to your question. He is using an optocoupler to convert a normally closed switch to a normally open signal, and to provide electrical isolation, the way a relay does. An optocoupler consists of an LED and a phototransistor. The phototransistor...
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