madbeanpedals::forum

General => Open Discussion => Topic started by: zombie_rock123 on September 21, 2019, 11:55:39 PM

Title: CA3046 / differential amplifier projects?
Post by: zombie_rock123 on September 21, 2019, 11:55:39 PM
Appealing to those with a greater knowledge than I. Does anyone have any leads on any projects/schematics that use the CA3046 chips? Or LM3046 obviously. Got a fair few tin can versions and all I can find is a couple of references on a synth forum. Not adversed to synth projects if they can be adapted :-)

They're a differential amplifier but with an extra transistor on the emitter of the pair. I know that the Standard Fuzz & BD2 use differentials but I don't know what I'd do with the base of the transistor on the tail to begin to try and work it in.
Title: Re: CA3046 / differential amplifier projects?
Post by: Scruffie on September 21, 2019, 11:59:50 PM
Good for either Moog style ladder filters or octave fuzzes like the super fuzz etc.
Title: Re: CA3046 / differential amplifier projects?
Post by: alanp on September 22, 2019, 12:32:42 AM
The matching is usually reasonably good with the 3046. Only Q1 and Q2 are connected internally, the other three are completely separate. There is no hard law that Thou Shalt Use this as a diff amp, by the way, just make sure that pin 13 is always the lowest voltage on the chip.
Title: Re: CA3046 / differential amplifier projects?
Post by: zombie_rock123 on September 22, 2019, 10:02:55 PM
Thanks guys, appreciate the tips. I did fuck up slightly as I meant to write CA3026 rather than 3046. Alan, do you have any use of a few?
Title: Re: CA3046 / differential amplifier projects?
Post by: alanp on September 22, 2019, 10:48:48 PM
I've got a few synth modules that use them, and I have a couple I'm keeping spare in case the working ones blow up...