MK179 supply voltage

Kits Mini Kits Range
1

I have an electric bike and would like to run this kit as the equivalent of an ignition switch using an existing bike battery rather than a separate individual 12V battery. Depending on my use of the bike it runs at a nominal 36 Volts or 72 Volts. The best choices for me (in order) would be to run this kit off:

  • approx 28 V to 80V (this would then be suitable for either battery setup with no additional setup needed so would be the best way).
  • A switchable setup for the two possible running voltage ranges of approx 28V-40V (nominal 36V) and 56V=80V (nominal).

Is it only the UA705 that would need changing? Any suggestions of a suitable regulator?

Or would I need to use an external Voltage converter/regulator to drop to the 12V?

Another possibility (but not a preferred one) would be to run it off a separate LED light battery which is 8.4V max with 7.2V nominal 5.5V cutoff- again, would it work as is, or need a resistor change?

Many thanks for your advice!

2

The max. input voltage for the UA7805 is 30-35V if I’m not mistaken.
A discrete voltage regulator in front of the existing voltage regulator will probably be the best solution.
You could build it with e.g. a 12V zener and a power transistor rated for 100V/1A. The transistor can be wired as emitter follower. (please Google for circuit examples if you are not sure how to make this).