Re: [CAD_CAM_EDM_DRO] Electronics gurus please help

Jon,

You are completely correct, technically, and have provided a good
insight into the broader design issues. I tried to focus on Vajk's
problem which to me appeared to be a wiring error rather than an issue
related to transients, crosstalk etc etc. As Vajk subsequently
indicated, the error was due a reversed chip, so I stand by my comment.

In trying to assist folk, I also try to apply the KIS principle in order
to try not to overwhelm the person with too much info. This problem
and the group's answers (including yours) all contributed to a good
insight into a common problem for everyone who designs electronics.

Cheers, Peter




Jon Elson wrote:

>Peter wrote:
>
>>Hi Vajk,
>>
>>The clock frequencies you are using have no relevence to your problem
>>and the shapes of any traces.
>>
>
>No, not correct. In a purely digital system, that would most likely be true.
>Remember, he's switching, perhaps, up to 10 AMPS with those digital
>signals. The energy radiated when a transistor turns off a massively inductive
>load like a stepper motor coil is huge! This is a classic situation that drives
>electronic designers to drink. A low-level digital signal switches a substantial
>current through an inductive load. Large voltage transients (easily hitting
>hundreds of volts) capacitively couple to various nearby chips and drive their
>input protection circuits to clamp these voltages, driving large currents into
>the digital logic +5 V and ground lines, upsetting still more circuits, etc.
>
>Jon
>
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