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  1. kellys_eye

    Wire spool - what is it worth?

    ????? only if you advertise 'for sale to some gullible person' :D 50cents/metre if you're lucky. You might get $100-$200 for the whole reel.
  2. kellys_eye

    Need Help regarding Yamaha RXV371. No Sound Output

    What are you using to measure those voltages? What range are you switched to? Where are you taking your 0V reference from?
  3. kellys_eye

    GSM and 3G Communication Modules

    GSM modules are neither expensive nor large these days: https://www.ebay.co.uk/itm/M590E-GSM-GPRS-Module-900m-1800m-Sms-Message-Diy-Kits-M590-CPU-MCU-Test-Pop-UK/401400390658?epid=1382868519&hash=item5d7553e402:g:MDgAAOSw9~5ZSWRO and interfacing to them is a case of serial data and AT Command...
  4. kellys_eye

    Need Help regarding Yamaha RXV371. No Sound Output

    Those are the voltages on the 'standby' power supply. You need to check the supplies (+/-12V) on CB134 (MAIN 1) and on the 'digital' connector CB131. Test and report.
  5. kellys_eye

    Controller board for IPL laser

    Keep your hands/fingers away from the 'naughty' bits (mains voltages) and it's not dangerous! The 5V (and 3.3V) may be available at the 'bottom end' of the resistors adjacent to the specific supply LEDs. Measure the voltage at these resistors with respect to 0V (ground) and report back. I...
  6. kellys_eye

    Laser toner refills

    That's a good price - thanks for finding it. Fortunately - depends on how you look at it - we can offset the cost against our business expenses/tax. Most printing we do is for the businesses that me and Mrs k_e run from here and (one) of my businesses (takeaway curries believe it or not!)...
  7. kellys_eye

    Controller board for IPL laser

    The section of board shown below forms a small SMPS that delivers a 5V supply to the board. Mains comes in at the right hand side, is rectified and smoothed, switched via the 8-pin IC that drives the transformer (blue) and rectified (two diodes and a couple of capacitors) to give the 5V that...
  8. kellys_eye

    Controller board for IPL laser

    Sounds like there's a short somewhere on the board. Unless my eyes are deceiving me the (black) capacitor (smaller of the two) in this picture seems to be swollen..... can you confirm? Better still, replace it anyway...... The one behind it doesn't look too chipper either.... replace that too.
  9. kellys_eye

    Security System for a Boat..

    The LoRa series of transceivers are ideal for an alarm/monitoring system although they don't have the bandwidth for video - which is pretty irrelevant in this application anyway. You could connect bilge pumps, movement, smoke detectors etc to it and get an instant alarm and even use it whilst...
  10. kellys_eye

    Morse code reader

    I've seen many morse code readers/writers over the years from the Elektor morse code reader (74-series logic) to the modern Arduino/processor versions. As for writing, there are 'discrete' circuits out there (74-series again) or simple software routines (I wrote software for an Apple II many...
  11. kellys_eye

    Controller board for IPL laser

    Have you measured the voltage coming out of the regulator to see if it actually is 3.3V? Use a multimeter and measure the voltages at each of the pins on the device. Also measure the voltage of the green battery. This likely retains various system settings which may be lost if the battery is...
  12. kellys_eye

    Shut off 12 volts 5 amps

    A PTC thermistor is a 'resistor' that changes value with temperature. It is usually only capable of carrying a few 10's of mA of current so is employed in a comparator circuit who's output is used to switch another device - relay, transistor, triac etc.... these devices then control the higher...
  13. kellys_eye

    Need Help regarding Yamaha RXV371. No Sound Output

    Did you isolate the PSU outputs? i.e. disconnect the power supply section from the rest of the electronics?
  14. kellys_eye

    Squawk Box

    How did you check the battery and speaker?
  15. kellys_eye

    Laser toner refills

    My printer is the HP4025C and I've just taken delivery of a toner refill bottle for it (yellow) as a test. I have a full set of empty cartridges to work with so can practise on this one to get it right! Replacement chips are also available (£1.50 each!) but you can over ride the chip in the...
  16. kellys_eye

    Shut off 12 volts 5 amps

    The device you state is the correct one but it doesn't work 'on its own' - it requires controlling circuitry. You still haven't stated whether you are working at 40F or 40C (I suspect 40F). For the higher temperature you could get a thermal (bi-metallic) switch that is 'passive' i.e. needs no...
  17. kellys_eye

    Shut off 12 volts 5 amps

    A thermistor. Usually used in conjunction with a level detection circuit designed around the required switching temperature. You can purchase digital-readout, adjustable temperature controllers all over eBay and t'internet for a few $ that also incorporate a switching relay to let you...
  18. kellys_eye

    Don't connect vs no connect

    For the 'mega pin' devices (like ball-grid-array (BGA) processors) the use of spare (NC pins) can be very useful - but as you get down in pin count it becomes rare to have to use them for such a purpose given the track width and ease of placement of a via. I have seen pcb's that utilise the NC...
  19. kellys_eye

    Project help wanted

    Wi-fi cameras are already in existence. The majority are 'powered' though (no battery) as the power levels required to sustain permanent wi-fi distribution of live images is beyond a practical battery solution. Certainly they COULD be used but the battery pack size and recharging thereof makes...
  20. kellys_eye

    Kindle fire HDX 7, 3rd gen

    Sell it and buy a Hudl (built-in HDMI port).
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