RM 9090a wah

SFTFN · Post by **SFTFN** » 16 Jan 2013, 11:47

Pics if anyone's interested. It's an ok wah, but nothing special. I like my 1970s Jen much more.

ppluis0 · Post by **ppluis0** » 16 Jan 2013, 13:46

Hi SFTFN,

Can you tell us what model of transistors are soldered in this board ?

FWIW, the inductor is made from an EPCOS (formerly Siemens) ferrite core: the material compound is N48 that is well suited to work at low frequencies, and the other number stamped "630" indicates a coefficient since this core has grinded an air gap internally.

To obtain the usual value of inductance needed in a wah pedal (500 mH) we must crank about 891 turns of enameled wire in this particular size of core.

Cheers,
Jose

SFTFN · Post by **SFTFN** » 16 Jan 2013, 14:46

Interesting information about the inductor.

All transistors are marked C549C PH66, so they're bc549 type. The two blue caps on the bottom part of the board are 10n btw.