sn7405 + crystal = sine wave?

Jan 26, 2005 3 Replies
J

I'm using Tina Pro and playing with crystal oscillators. I can get a nice



4MHz square signal with an SN7404, but when I replace it with an SN7405 the signal is a sine wave. Is this normal?


-John


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M

The 7405 has an open collector output. If you simply put a 7405 in place of a 7404, and don't do anything about those open colelctors, then the oscillator is bound to put out odd results, if it works at all.

Michael

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J

Thanks! I thought that was a little strange.

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T

If you put a 470 Ohm, or thereabouts pullup resistor on the 05, it will probably work the same as the 04.

Tam

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