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Author Topic: Bad 8038?  (Read 853 times)

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Offline Analog KidTopic starter

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Bad 8038?
« on: December 10, 2025, 07:00:24 am »
Trying to make a poor man's function generator using an ICL8038. Have it running on a breadboard. Here's the square wave (not particularly high frequency):



Bad chip? Fake? Looks like the real deal. Sine & triangle outputs are OK.
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Offline pcprogrammer

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Re: Bad 8038?
« Reply #1 on: December 10, 2025, 07:13:59 am »
Looks like a bad connection or to high a pull up on the open collector square wave output.
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Online moffy

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Re: Bad 8038?
« Reply #2 on: December 10, 2025, 07:14:29 am »
If you are using a x10 probe, then it needs tuning, or AC coupling.
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Offline Analog KidTopic starter

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Re: Bad 8038?
« Reply #3 on: December 10, 2025, 07:31:03 am »
That was it. I was using the probe at the X1 setting.



Still an o'scope n00b here.
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Offline Ian.M

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Re: Bad 8038?
« Reply #4 on: December 10, 2025, 08:40:09 am »
You've still got excessive droop on the flat parts of the squarewave.  I'd bet the scope input is set to AC coupled.  Try DC coupled!
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Offline Analog KidTopic starter

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Re: Bad 8038?
« Reply #5 on: December 10, 2025, 08:57:41 am »
Yeah, that definitely makes it better. Chip is OK.
Function generator coming up ...
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Online coromonadalix

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Re: Bad 8038?
« Reply #6 on: December 10, 2025, 10:38:51 am »
be sure your probes compensation is adjusted okay  before doing tests
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