Hi Everyone,
Ive got a speed controller on a customers 24v e-bike that uses SDP85N03L 83A 30V N-Channel Logic Level Enhancement Mode Field Effect Transistors.

We want to use a 36v motor and the only parts in the simple controller blocking this are the Mosfets which are 30v max and the 7808 regulator.

Can anyone suggest similar, but suitable higher voltage replacements for these two components ??

Regards,
Byt

 

MOSFETs - don't know which package you have.
Here's a TO-220 package that might do it for you
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=869-1048-ND
Here's a D2Pak
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=497-6549-1-ND

As far as the 7808 - why not just power that section of the electronics from the battery nearest ground, instead of from the +36v terminal?

 

Thanks Sarge,
that mosfet looks absolutely perfect and has a faster switching time too, so less heat!

I understand what you mean by the powering from the battery closest to earth, but the battery the customer bought is a sealed expox(?) filled 36v lithium ion battery, so thats not an option.

Cheers!
Byt

 

OK, so get a 7805 regulator, and connect it between the 7808 and the battery. Then connect the 7805's GND pin to ground via a 3.3k resistor. That should make the 7805 output about 22.5v, give or take a volt.

You will also need an 0.33uF cap from the input of the 7805 to ground, and an 0.1uF cap from the output to ground.

This way, the voltage differentials will be split between the two regulators.