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  1. Ylli

    How do I reduce the speed of a 12v childrens car

    That's where I was going, BUT...... Since you can not measure any resistance between the green wire and either of the other two, I have to agree with kellys_eye and BobK that the throttle block is not a simple potentiometer, but rather an active device. The voltage divider will need to be...
  2. Ylli

    What are these sections of this power supply?

    Assuming only one channel, here's a possibility for your filament transformer: https://www.alliedelec.com/stancor-p-6134/70213223/
  3. Ylli

    AC Measurement Question

    What meter are you using? make/model Your meter may be getting confused by the DC when set to an AC Volts range. Two things you could try: 1. Using one (or both in series) of those batteries you spoke of earlier, connect the batteries in series with the output of the wallwart. You should...
  4. Ylli

    AC Measurement Question

    Should be zero or near zero AC voltage across that cap. Can't imagine where you are getting 39.2 VAC from. Even if the diode were shorted, with an input of 14.2 VAC, the most you would see across the cap would be that same 14.2 VAC. Any equipment or appliances nearby that could be radiating...
  5. Ylli

    How do I reduce the speed of a 12v childrens car

    Are you sure this is 2.42 *ohms* or perhaps 2.42 K ohms?
  6. Ylli

    How do I reduce the speed of a 12v childrens car

    Yes, that is why I was looking for the resistance readings on the throttle 'pot'.
  7. Ylli

    How do I reduce the speed of a 12v childrens car

    http://www.uumotor.com/store/121-60v72v-1500w-electric-trike-motor-controller-with-30-mosfets.html is as close as I can find. Again, I ask:
  8. Ylli

    AC Measurement Question

    What do you measure across the 470uF capacitor. Do you see a significant AC component there? If you do, disconnect the input pin of the regulator (so you have just the diode and the cap). Is there still a large AC component across the 470uF? An AC component on the output of the regulator can...
  9. Ylli

    What are these sections of this power supply?

    Careful, the 6L6 filaments draw 0.9 amps, but the 6SJ7's only draw 0.3 amps. You *could* put the 6L6's in series, and the 6SJ7's in series - then parallel these and connect to a 12 VAC 1.5 Amp transformer. Just to add, for the B+ side, you could use a transformer designed to convert from a 220...
  10. Ylli

    Kenwood Receiver Heating Issue

    Great!
  11. Ylli

    How do I reduce the speed of a 12v childrens car

    Do the resistance measurements with the unit unplugged - just like it is shown in your picture.
  12. Ylli

    How do I reduce the speed of a 12v childrens car

    Do you have an ohmmeter? Connect one lead to one of the wires, and the other lead to a second wire. Record the resistance with the 'accelerator' in both ends of it's extremes. Now do the same with a second pair of leads. And with the third pair. Also note the trend as you move the...
  13. Ylli

    AC Measurement Question

    The ceramic disk would be fine.
  14. Ylli

    AC Measurement Question

    Others have talked about the power dissipation. So on to the 0.1 uF caps. Because of the constraints of the way they are constructed, large caps (such as your 470 uF) are not effective at higher frequencies. Effective bypass requires the use of multiple capacitors -- sometime you will see a...
  15. Ylli

    What are these sections of this power supply?

    Most of the complication is an attempt to reduce any possible 'hum' from the amplifier. The transformer would need to have two secondaries, first 250 VAC @ 150 mA . Second winding 6.3 VAC @ 3 amps. If you are going to build only one channel, then the 6.3 VAC winding can be @1.5 amps. (A 6L6...
  16. Ylli

    AC Measurement Question

    If you have 16.7 volts on the input and 5 volts on the output, then you have 11.6 volts dropped across the LM317. P = E*I = 11.6 * 0.05 = 0.58 watts. Half a watt dissipated in a small package without a heat sink can indeed get quite warm. Strongly suggest a good heat sink. Reducing the AC...
  17. Ylli

    Kenwood Receiver Heating Issue

    Well, the 30K adjustable was obviously not adjusting down to zero as it should, but the higher resistance end seems to be OK (you said the voltage dropped and then started to rise again). So we want to use the high end of the VR. My number crunching told me that the resistance needed between...
  18. Ylli

    Kenwood Receiver Heating Issue

    Progress, but it seem that pot (VRe2) is still a bit flaky. Really should be able to get Qe4 emitter down to 0.4 volts and lower (really should be able to get it down to zero). Do you have any fixed resistors available? If we put a fixed resistor in parallel with VRe2, we will change the...
  19. Ylli

    Kenwood Receiver Heating Issue

    With VRe2 set to minimum resistance, that should take the base of Qe4 to ground, or 0.0 volts. With the base at 0.0 volts, the emitter should certainly be at 0. Again, adjusting VRe2, how low can you get the base voltage of Qe4?
  20. Ylli

    Kenwood Receiver Heating Issue

    Simplified schematic. Should look pretty familiar. Whoops, the resistor labeled R649 should be labeled R213
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