Hello, This was started a long time ago, short attention span and no hurry, finally got to stomp on it today, fired up on first go 'round, no rocking before ... Aaand no magic here, just my iteration of an ultra-complcated circuit... treble booster with
two transistors.
Name? A while back a friend spent some time teaching ESL to the locals in Georgia... the other Georgia... so from a list of Georgian communities i snared Tkibuti as i liked how i thought it might be pronounced. Little to be gleaned about Tkibuti other then destitute, post-industrial wasteland.
All the Russian Ge transistors i've received, PNP's & NPN's, have had low gains of no more then 30 so built this Ge Darlington Rangemaster based on the article by Steve at Small Bear.
https://www.smallbearelec.com/HowTos/BreadboardGeDarlingtonRMs/BreadboardGeDarlingtonRMs.htm(Built with PNP's, positive ground, schematic is for NPN's)
Body control.
Darlington
Based on this schematic my values for the various parts;
Input caps; 3n polystyrene & 27n polyester. Tried every variety of cap i had, various types of ceramic, plastic, polystyrene, to my ear no disernable difference so used most interesting looking 3n cap i had kicking around?
Output cap; 39 polyester.
Emitter cap; 3.3uF
Emitter resistor 3k
Bias resistors 470k & 62k
Rc 1k2
Rd 20k
Collector voltage fell nicely in desired range with 2 GT308b's.
On the rats nest breadboard was crazy noisy/buzzy but with the pcb and shielded enclosure as quiet as my standard Rangemaster. WAs concerned about the noise so breadboarded a standard so i could swap in the transistor from the my previous quiet build and vice versa and the noise stayed with the setup not moving with the transistor so felt hopeful that once properly built the noise would go, success! On a further note the gain of these Ge's seems to be enough for use in the standard arrangement, more play...
Used a battery power-switching arrangement idea from Geofex, using a 2N3904 (positive ground cicuit).
http://www.geofex.com/FX_images/PNP_power_switching.pdfLayout done in ExpressPCB then the usual tweaks in Inkscape. Sunk four sockets e/b/c/e, so can use any transistor pinout without having to contort the leads. Layout now verified, fired up nice and quiet.
Photoboards exposed ~1" away from the flourescent tubes above my workbench, absolutely no need for any special UV setup for board exposure, UV will cut down exposure time considerably but that's it, ~9min. lots of leeway, for flourescents, UV 60-90 sec.
Resolution, ruler divisions 1/64". Lacquered boards.
Enclosure madness; one of Mac Walker's terrific wedges. Cut a battery sock from an old bicycle 1" inner tube, heavy duty stick on velcro to mate it the enclosure then a rubber grommet stuck to the bottom plate to firmly entrap the battery. Battery snap was something put together for another project and never used, perfect fit for this.
Sanded enclosure with 220, cleaned with acetone-> self-etching primer-> BIN Shellac based Sealer/Primer. Then... artist acrylics and mediums, gouache paints, rocker panel paint, spray webbing, charcoal pencils, watercolour pencil crayons, permanent markers, Gun Metal Bluing, Target 7000 lacquer, propane torch, JB weld, frisket film and masking tape stencils, liquid frisket, stamps, toner transfers, collage. Applied/removed with paint brushes, air brushes, palette knives, ruling pen, pop can pen, brayer, toothbrush, scrub brush, fingers, resistor lead, sandpaper, rifflers/files, Dremel burr, xacto knife, and dental picks. Gimp and Inkscape used to organize and manipulate ideas/images etc.
Cheers! dave
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