TRANSISTOR, VALVO: OC45 / OC44 Germanium Transistor Datasheets

Valvo OC44 OC45 datasheet d096c7842994

Valvo transistors were produced in Germany, as a subsidiary of Philips (not unlike Mullard in England).   More information on Valvo can be found here.  My experience with Valvo, is that they are pretty much identical to their English counterparts. The OC45 is a PNP germanium alloy transistor intended as IF amplifier in AM broadcast receivers. … Read more

TRANSISTOR, BRIMAR: AC113 Germanium Transistors

Brimar Mazda Thorn AC113 datasheet b356e4aa4b1f

Brimar transistors were made by Thorn and were also commonly branded as Mazda.  A full write-up can be found here The AC113 is an audio frequency amplifier or driver type germanium transistor. AC113  GERMANIUM TRANSISTOR DATASHEET TRANSISTOR EQUIVALENTS Being a fairly generic audio amplifier, they’re listed as being similar to a number of common amplifier … Read more

COLORSOUND x D*A*M: Fuzz Sound

COLORSOUND DAM Fuzz Sound 2 knob 015 vero layout v1 6576df17b251

Following on from the previous post, this is the D*A*M version of the Colorsound Fuzz Sound.  Thread on the D*A*M forum can be found here.   Basically take a D*A*M Fuzz Sound, and change the Fuzz pot to an internal trimmer.  Unlike the regular Park 2 knob with a large 25u coupling cap between the darlington … Read more

PARK: Fuzz Sound, Two Knob Version, tag board layout

PARK 2 knob fuzz sound tag board v1 70eeb490f49f

Request for Phil – one tag board layout for the Park 2 knob fuzz sound.   I generally prefer to keep the links below the board, as it looks neater.  I don’t mind linking two adjacent lugs on top, as you hardly notice it. One suggestion for this.   The D*A*M Colosround Fuzz Sound has a few … Read more

HOFNER: Germanium Pre-amp

Screenshot 2023 07 25 at 6.27.53 pm b127fb1c0943

I only came across the Hofner Preamp quite recently, despite seeing some other builders making point-to-point style germanium preamps based on this circuit – the prime example being the R2R Electric preamp. There’s a good write up here, but in summary: Back in the day before guitar amps were affordable, and TV was a thing, … Read more

SOLA SOUND: Tone Bender MK1.75 ‘El Diablo’

Sola Sound MK1.5 El Diablo v2 35853f0e8e2a

The El Diablo…   A Dave Main creation, part Sola Sound MK1.5 Tone Bender / part Vox Tone Bender – hence the MK1.75 moniker.  And why El Diablo? apart from the colour, this thing sounds mean as hell. They appeared to use a couple of different transistors for Q2, but the OC75 remains up front – … Read more

VOX: Tone Bender, Tag Board Layout

VOX Tone Bender tag board layout v1 36263b277bbd

While I was working on another fuzz face layout (the Sonus Jimi Mod 1968),  I thought I might do a quick adaptation for the Vox Tone Bender, as there was room for the additional resistor. Quite fond of the Vox, so I’ll probably build this once I’ve finished my current project.  Usually I like to … Read more