# [help]how to step up voltage for better motor performace

#### p63gonome3

Joined Dec 8, 2011
5
uhm... my input voltage is 6-12v and i was thinking on how would the output voltage in my l293d become 24v to operate my dc motor without risking the other circuits connected to it. i checked about using a voltage multiplier however, i wonder if the output would still be the same coz my professor said that the current might lessen if i use a doubler... thanks in advance

#### mcgyvr

Joined Oct 15, 2009
5,394
Specs of motor?
Specs of power supply?

#### shortbus

Joined Sep 30, 2009
8,197
Your professor is correct. A doubler will double voltage but halve amperage. The L293 can be used with a separate 24volt supply though, keeping the "logic" part of the circuit at the present voltage. But like mcgyvr said, will your motor take the higher voltage?

#### MrChips

Joined Oct 2, 2009
22,550
Your professor is correct. A doubler will double voltage but halve amperage. The L293 can be used with a separate 24volt supply though, keeping the "logic" part of the circuit at the present voltage. But like mcgyvr said, will your motor take the higher voltage?
This is not correct. The maximum current deliverable will be reduced in half.
The actual current will be double so long as the maximum current is not reached.

Suppose your load is 1K-ohm. With a 12V supply the current will be 12mA. If you double the supplied voltage to 24V using a voltage doubler, the current will increase to 24mA provided that the 12V supply can provide greater than 24mA (taking efficiency losses into account).

#### shortbus

Joined Sep 30, 2009
8,197
This is not correct. The maximum current deliverable will be reduced in half.
The actual current will be double so long as the maximum current is not reached.

Suppose your load is 1K-ohm. With a 12V supply the current will be 12mA. If you double the supplied voltage to 24V using a voltage doubler, the current will increase to 24mA provided that the 12V supply can provide greater than 24mA (taking efficiency losses into account).
Could you please show a circuit that can do this?