Voltage Conversion Hack

Have you ever wanted to convert 3.3V to 5V? Well I had to recently come up with a hack since I did not have the correct driver logic chips.

Here's how...

Please note that this will not work for applications where a lot of current is needed!

I am playing around with a National Instruments' myRIO which I want to use to drive HB-25 motor controllers. The HB-25s are controlled using pulse-width-modulated (PWM) signals, similar to controlling servo's. However, the myRIO output pins only supply 3.3V and the HB-25's need 5V on their input pins.

The correct way of solving this problem is to use some or other buffer/driver chip, like the 74HC/HCT244. Unfortunately I did not have one and ended up using a 74LS32 (Quadruple 2-Input Positive-OR Gate chip) to push the output voltage up to 5V. I connected both input pins together and connected them to the desired pin on the myRIO. The gate's ouput pin was connected to the HB-25 control input pin.

Voltage converter hack

This works because the smallest input voltage that will be detected as a 'HIGH' is 2V, for which the chip will give a 'HIGH' output close to 5V, but ONLY IF SMALL CURRENTS ARE DRAWN. You will see a drop-off in supplied voltage as the current drawn increases.

Happy hacking!!!

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