Category Archives: radio

EAGLE CAD Toroid drawing tool

This small bit of software can auto-generate a toroid outline for EAGLE. You can select horizontal or vertical mounting, and specify the toroid dimensions and the number of wire turns. It will generate an EAGLE script file (.scr) that can … Continue reading

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Toroid (Amidon) calculations

The excellent website here andĀ  hereĀ  allows you to figure out what core and number of turns for a given inductance, for ferrite and iron powder toroids respectively, and also to see the impact of adding or removing turns. … Continue reading

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Quadrature detector coil

Here are photos of the elusive 235SU1 coils. One will be disassembled in the name of science! It can be seen that the primary coil has the tuning slug pulled out a bit. This kind-of agrees with parts of the … Continue reading

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Tuned Front End for FM receiver

The Ryder paper (here) uses a tuned front end. The specified coils (Toko E526HN-100319) seem to be unobtainable, but surprisingly, E526HN-100119 are available (just about), and it looks like they are very similar (I don’t know what the difference is). … Continue reading

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Modern take on Ryder’s FM Receiver

The link here shows an FM receiver with a high level of claimed performance. The diagram here shows a snippet from the paper. The problem is, most parts are obsolete. It is an opportunity to try to improve areas of … Continue reading

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More TEF6606 info

For the circuit that was constructed for testing (based on the Application circuit in the data sheet, the v3 copy of the datasheet is here), the TEF6606 was powered directly via a 9V alkaline PP3 battery (not ideal, because the … Continue reading

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Simple op-amp based headphone amp

This single-IC circuit is pretty basic but is enough to get the TEF6606 audio up to (very loud) headphone levels. It is just a test circuit, not intended for high quality. There is no volume control, so the volume is … Continue reading

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Implementing I2C

The ATmega32u2 doesn’t have a two-wire interface (as far as I can tell) or I2C, so this method was used to have an I2C bus. The circuit shows the SCL line, and the same circuit is duplicated for the SDA … Continue reading

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TEF6606 receiver

As an experiment, I constructed up this FM receiver. It worked first time – no coil adjustments are necessary. It makes it remarkably easy to get it running. Will post more details soon.

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Diode ring mixer

A picture says a 1000 words.. this is an ancient mixer on e-bay recently, I have one for experimentation. It looks well designed (baluns to keep the mixer balanced, and tight twists), and is from a military device (UFT 721 … Continue reading

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