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### Author Topic: Motor Driver issue  (Read 1687 times)

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#### Tweakie.CNC

• 9,012
• Super Kitty
##### Re: Motor Driver issue
« Reply #10 on: October 07, 2018, 01:33:32 AM »
Can you please tell me why do we not get meaningful readings when using continuous mode on a powered up circuit?

The fundamental principles of the electronics of a DMM are bit beyond the scope of this forum so you will have to do your own research on that subject.

Tweakie.
PEACE

#### joeaverage

• 7,464
##### Re: Motor Driver issue
« Reply #11 on: October 07, 2018, 01:48:03 AM »
Hi,
the ouputs of the board are TTL....that is to say active outputs.

If the output is high it will be somewhere between about 4.5V and 5V and be able to produce about 20mA of current. If you try to draw more current than
that you'll probably fry it.

If the output is low it will be between about 0.5V and 0V and able to sink about 20mA of current. If you cause it to sink more than that you'll blow the
IC.

There is a very useful little circuit that you can make which will indicate when the output is high and when it is low. Provided you use it on circuits
of 5V or 3.3V it works OK. You'll blow it at higher voltages One LED is on when the output is high and the other is on when it is low.

Craig
My wife left with my best friend...
and I miss him!

#### joeaverage

• 7,464
##### Re: Motor Driver issue
« Reply #12 on: October 07, 2018, 01:55:46 AM »
Hi,
sorry should explain how to use it.

One end, doesn't really matter which, goes into the output you want to test. The other end you hold on a 5V terminal. If the output
is low one LED will light up. If the output is high then neither will light up. If that's the case hold the floating end on a 0V terminal.
If the output is high a LED (opposite color) will light up.

Craig
My wife left with my best friend...
and I miss him!