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Old Dec 27, 2002, 08:05 PM
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Mike,

You must leave the DC-DC's schottky diode installed (do NOT remove it). The only components you should remove are the NPN transistor, inductor, and the large electrolytic (if used) that is on the "battery side" of inductor. Place a jumper wire across the inductor pads.

Battery voltage must be between 2.5V and 5V, under load. Never allow the voltage to exceed 5V.

Make sure that you have at least 47uF on the cathode side of the schottky diode. A .1uF ceramic should be across the battery input on the PCB. If power supply noise is really bad, you may need to re-install the inductor for additional filtering.

Here is how I would attack this:
(1) I would start with a stock BitChar-G Rx (clone or Tomy brand). I would then operate it on the single LiPo cell to verify that all was well. I would test it with the motor on and off, at various ranges.
(2) Then I would remove the DC-DC's NPN transistor and verify that all was well.
(3) Then I would remove the inductor and jump the pads, and verify all was well.
(4) Then I would replace the big cap on the battery side of the inductor with a .1uF ceramic, and verify all was well.

If at any step you get into noise issues then STOP and work out a solution before moving on.

Mr. RC-CAM
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