I'm not sure about the latter question - I assume the 2 matched transistors would be fine - but mouser stocks PN4250A. it's nearly identical according to the datasheet, just has higher capacity for collector-base voltage, and collector emitter voltage. The price is $0.41/ea: https://www.mouser.com/ProductDetail/Central-Semiconductor/PN4250A?qs=sGAEpiMZZMshyDBzk1%2fWi8oN7VHZ91OktECUlj3XHEg%3d
Here are the datasheet for comparison-
‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On July 6, 2018 7:04 AM, Mike Burnham mikejburnham@... [cgs_synth] <cgs_synth@yahoogroups.com> wrote:
Hi there
For the Serge Noise circuit it specifies the noise transistor as 2n/PN4250 but these are stupidly expensive nowadays
Is it possible to use BC557? Are they noisy enough? BC557C probably best?
The VCA specifies a matched transistor package
Would matched 2N3904 be OK? Or do they have to be super matched?
Thanks