FOR SALE – The Stereo applies only to the record player. It’s a little dusty. Well, maybe more than a little, it’s been sitting there for decades. You have to click on the picture more than once to get it to enlarge. Update Mar 4 – I sold it to a guy who said he
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A long time ago I came across this schematic of a Surf Synthresizer circuit. I remember reading something about this earlier, and I wanted to build one just to see if it actually worked. It’s a set of three astable multivibrators with their output voltages summed and low pass filtered, and the result is used
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See my General note at the bottom for some info on audio compressors in general. I had this hand drawn schematic in my SCH files folder, dated from 8 years ago. The actual schematic was from “E.A.” dated 1968. I can’t figure out what E.A. is. I would imagine that the E stands for electronics,
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I found this schematic of a hearing aid on a newer website called Talking Electronics, and it looked familiar. I checked the one on RedCircuits.com, and found that they are identical, other than the copycat has gone to some lengths to pretty it up with color and graphics. I know that this particular schematic has
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I blogged this a long time ago, but my old blog is gone, so here it is again. I unsoldered a large number of these 600 ohm hybrid transformers from PBX boards. Each transformer has four 600 ohm windings, and is used to interface to the PSTN (telephone central office). Notice that there is a
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I see a number of good designs for vacuum tube (thermionic valve) regenerative receivers in the Yahoo group Regenrx. Tubes are hard to obtain and notoriously inefficient; reasons why they would be my last choice for a receiver. But one area they have a big advantage is for use in a ham or SWL receiver
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The Wien Bridge Oscillator (sometimes mistakenly misspelled Wein) uses negative feedback to generate a very pure sine wave. The circuit can generate a sine with distortion so low it is difficult to measure. The schematic I´ve attached does not necessarily have such very low distortion, but it is simple – three transistors – and generates
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I checked out the AGC microphone on Techlib website, and I like the circuit. I have some LF353 opamps I got from Radio Snack a long time ago (I used to look in the blister packs and see both LF353s and TL072s), and I could use it in place of the TL072. One thing he
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