He uses my SJT circuit in his web page. https://devopedia.org/joule-thief-circuit
Archive for the ‘Oscillators’ Category:
2023-08-26 FM Bug, Crystal Locked
From Talking Electronics. I’m not sure if this circuit can be frequency modulated the full amount for the FM broadcast band. It’s difficult to push a crystal off its resonant frequency. I’ll be trying it someday if I can find the right xtal. I would be more inclined to instead use a ceramic resonator. I
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2023-07-12 DC-DC Converters That Used Germanium Power Transistors
Me and my high school friend made a DC to DC converter that would give us 30 or so volts at a couple amps from a 12 volt battery. We used germanium power transistors which could not go much above 10 kHz. The Delco’s and the 2N458A’s were our favorites – we managed to push
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2021-12-06 MP3 Player To FM Radio Link (Mono)
MP3 Player To FM Radio Link (Mono) This circuit allows you to play your MP3 or any stereo audio source into a mono signal for reception on an FM radio. It has no antenna and has a range of a dozen or so meters. It operates off a 6 volt rechargeable Ni-MH battery pack but
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2021-04-30 Circuit Won’t Oscillate At UHFs
From FB post Apr 29 Joshua E. Hrouda I trained on Radar repair in the Army, and since then I’ve known that circuits with ‘lumped constants’ have problems with parasitic capacitance and inductance above a few hundred MHz. But I experimented with this circuit anyway. I think Colin should say, instead of ‘tight’, that the
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2021-04-28 Colpitts Oscillator For FM BCB
This is a low power oscillator using an air core coil and silver mica capacitors for stability. Parts values are subject to the frequency needed. There is no modulation. For FM the 10 pF capacitor would be lower and include a reverse biased diode as a varicap in parallel. The audio should be across this
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2020-03-29 AM Osc + Modulation + Buffer
This is from Electronics Illustrated Projects 1968. It shows crystal sockets, but instead a RF coil may be used and its value will be about 220 microhenrys. And C1 and C2 will have to be changed to bring the frequency down to the AM band. The germanium transistors are no longer available so silicon transistors
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2020-03-10 Simple AM Band Antenna Tuning Coil 240 Microhenrys
The standard ferrite antenna loopstick for a 365 pF tuning capacitor has an inductance of about 230 microhenrys. This in combination with the tuning capacitor tunes across the full AM broadcast band. It’s useful to be able to wind your own inductor so it can be used for an antenna coil, a trap to attenuate
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2019-01-15 Zenith Royal 200 Conversion to Silicon
I’m thinking of pulling up the end of the 100 ohm and looping the lead a few times through the ferrite bead. If that still doesn’t stop the ringing, I’m thinking about replacing the bead with an RF choke. Every time the ringing is reduced the reception gets better. I checked to see if I
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2018-01-08 RF Oscillator For AM Band
For FB group Building Transistor Radios When I started building regen receivers, the first thing I found I needed was a simple signal generator. I have a function generator, but every time I want a different frequency, I had to readjust the controls. So I built a few RF oscillators to put close to the
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