Hi!
I am building MXR Noise Gate and Dan Armstrong Green Ringer in same time. This is my first time
matching components and I have Peak Atlas DCA55 semiconducter analyzer.
MXR Noise Gate I am building according to: http://tagboardeffects.blogspot.com/2013/01/mxr-noise-gate.html
It says BJT:s should be matched. I have a lot of 2N3904 and 2N5088 BJT:s. It's referring to Hfe value?
How close Hfe should be that pair can be considered matched and circuit works properly? Peak Atlas
has accuracy +-3 % / +- 5 Hfe
Green Ringer needs matched diodes, It's referring to forward voltage, Vf?
Schematic: http://www.generalguitargadgets.com/pdf/ggg_gro_sc.pdf
How close Vf should be that diode pair can be considered matched and works properly?
I am going to put Schottky-pair and Peak Atlas has Vf accuracy of +- 2% / +- 4mV.
Hi & Welcome.. :icon_wink:
hFE is always an important parameter but, depending on particular circuit, it can be overcame..
VBE is another important parameter and it must be measured at a variety of working temperature..
Offset voltage (VOS) could be of some importance, especially for differential input pair configuration..
Reverse breakdown voltage should only be considered for circuits working near limits..
Leakage current isn't of so much importance for modern Si BJTs..
Noise density shouldn't bother you.. :icon_wink:
also welcome.
we can't see your circuit diagrams. if this is your noise gate, you are wasting your time matching the transistors. they provide vastly different functions at opposite ends of the circuit. one is input signal amp, the other is gating switch thing.
(https://www.diystompboxes.com/pedals/schems/MxrGate.GIF)
It says BJT:s should be matched. - interweb sez a lot of things.
I like the idea of a noise gate built with 741's too. Lol.
Maybe put a modern op-amp in it (TL072 would be fine) so that it doesn't add more noise than it removes!