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DIY Stompboxes => Building your own stompbox => Topic started by: iainpunk on December 06, 2021, 04:38:49 PM

Title: CA3028 in a pedal
Post by: iainpunk on December 06, 2021, 04:38:49 PM
so i have a bunch of these long tailed pair/cascode amplifiers in my collection, and i have not yet had the chance to try them out. so i was wondering if anyone else has used these IC's for audio use outside of radio frequency magic, before i re-invent the wheel here.

i imagine using them as OTA's, phase inverters and overdriving gain stages.

(http://www.datasheetq.com/image/Harris/CA3028A.png)

i love that mine all came in the TO-99 package, and therefore have a +3 mojo bonus on all stats

cheers
Title: Re: CA3028 in a pedal
Post by: Rob Strand on December 06, 2021, 06:24:48 PM
Nothing comes to mind.   I remember those being used for FM radios, good quality ones.   I checked the datasheet for the input offset voltage and it says "controlled for input offset voltage" but a value wasn't given - maybe need to try some datasheets from different companies.

I don't even remember seeing those used for test instruments, that job often went to MC1496 and all that family.   You might find a ring modulator for those.

The only tip I have is to look at similar chips.  There's a lot.  I'm sure Philips had some (no doubt TAxxxx).  I don't remember any cool application notes just a lot of RF circuits.  Once in a blue moon you will find a cool circuit in the old Electronics Design Circuit compilations, which are on the worldradiohistory site, but there's not a lot of audio there.
Title: Re: CA3028 in a pedal
Post by: iainpunk on December 07, 2021, 08:11:26 AM
i figured.

ill probably end up using it as a LFO variable wave folder in a fuzz/tremolo circuit i have in mind.

cheers