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  1. WHONOES

    Using a Varistor to solve a back EMF problem

    I am surprised that the starter motor relay / contactor fails. They are required to switch up to 700A or more of start current . An alternative could be a large or several larger MOSfet transistors. Also, have you tried Farnell and / or RS Components web sites for some diodes. They don't have to...
  2. WHONOES

    12V 10Amps Power Supply Works for 5 Minutes Only

    Can you see the markings on the heatsink mounted devices.
  3. WHONOES

    12V 10Amps Power Supply Works for 5 Minutes Only

    Looks as though it is using a secondary regulator on a small heatsink. These tend to have over temp cut outs to protect them. it could be that it is simply over heating.
  4. WHONOES

    Using a Varistor to solve a back EMF problem

    Have you ever considered using an old starter motor relay from a car. These have to switch hundreds of amps without failing for many years. You could probably get one from a breakers yard.
  5. WHONOES

    Faulty treadmill control board

    Can you disconnect the motor and measure the resistance on its terminals. It is likely to be quite low so, you should proceed by turning on the DMM. Switch it to the lowest resistance range available. Connect the DMM leads together making sure you have very good contact. Make a note of the...
  6. WHONOES

    Woo-Woo What electronics do these invisible earphones have in them?

    I think your money would be better spent on a bottle of wine.
  7. WHONOES

    Woo-Woo What electronics do these invisible earphones have in them?

    They could all be sham reviews. For you to hear anything, the device has to move air. I don't see any way that it could. Not only that, it very small and if it was inserted in your ear canal you would probably have difficulty getting it out again.
  8. WHONOES

    Faulty treadmill control board

    See if you can measure the current demand for the motor as well. Edit: Do you have any documentation that describes what the fault code means.
  9. WHONOES

    Woo-Woo What electronics do these invisible earphones have in them?

    I think it looks remarkably like a small button cell battery. SCAM? probably.
  10. WHONOES

    Problem on high voltage leg on triple output power supply.

    It's somewhere between difficult and impossible to diagnose your power supply problems without reference to a schematic of some sort otherwise the nature of the design philosophy would be pure speculation on our parts. Having said all that, it might be that regulation might be controlled from...
  11. WHONOES

    Transistor series voltage regulator

    I think the gentleman really wants to know how a transistor works. I suggest he has a look at the link below. https://www.explainthatstuff.com/howtransistorswork.html
  12. WHONOES

    Micky taking ebay sales?

    It has clearly been taken (de-soldered) from a PCB and suffered physical damage in the process. I expect it has been "Rescued" by some loony in China. I would be very surprised if it worked. Not only that but who would want to use a 709 anyway.
  13. WHONOES

    Problem on high voltage leg on triple output power supply.

    If all the output voltages are generated from one transformer then all will be regulated from just one of the outputs. If there is no load on any of the outputs then no regulation will take place. Therefore the output that is responsible for regulation needs a load of some sort.
  14. WHONOES

    How to redraw if a drawing have legal limitations ?

    Surely if your company has purchased the rights including all documentation to the equipment concerned then you should be able to, as the owner, redraw diagrams for your purpose at your convenience.
  15. WHONOES

    Problem on high voltage leg on triple output power supply.

    As mentioned on another thread, these type of power supplies frequently require a minimum load in order to function correctly. With multiple output types, the regulation would be controlled by just one of the outputs which will most likely be the lowest one. Try putting a load of 5% of rated...
  16. WHONOES

    Is that a fuse or resistor

    You most likely need a load on the output for the switching circuit to work at all. Most of these types require a minimum load probably around 5% of rated output. Though having said all that I would expect to see some sort of voltage on the output, it would likely be very low though. According...
  17. WHONOES

    Transistor-triggered photogate

    The BTA 16 is, according to its data sheet, a Triac and not a Thyristor and its gate current seems to be 25mA. Depending on what you want to drive from the output, other solutions may be more suitable.
  18. WHONOES

    Need 12V Signaling Supply from 110VDC to Control DC Motor

    If I was trying to do as you are, I would use a small transformer to generate a supply for the 12V supply needed for the PWM drive circuit. No danger then of overdriving the gate and no need to drop 70V down to 12V with the possibility of that circuit failing and destroying the FET by applying...
  19. WHONOES

    Transistor Identification help requested

    Just try googling the part number followed by the text "Datasheet" and see what happens. If no results then that is probably the end of the line unless any one seeing this post and who may have the required info responds.
  20. WHONOES

    Design fix on a battery powered COB LED

    Perhaps a joule thief may be suitable. It is a simple circuit that will increase the voltage available from a AAA battery and could be used to drive you LED string. I think the joule thief has been dealt with a number of times on this forum. You could also use a small LiPo battery in conjunction...
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