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A vintage unmarked inductor/transformer had been lying neglected in my junkbox for decades and I had to resurrect it. Resistance checks showed that 2 windings, with a tap each, are terminated in its 6 pins. One measured 70 Ω with a 5 Ω tap and the other less than 1 Ω. A threaded core, with a...

Thanks, Rob! 73, Nandu.

A fully tarnished, shiny black silver artefact was tried out as a detector in place of the germanium transistor in my series-tuned, shunt-fed crystal radio. Fortunately the presence of an untarnished spot facilitated the metal to metal connection. A length of pencil 'lead' was used to probe...

This series-tuned, shunt-fed crystal radio was built using parts salvaged from a vintage / battered SCR - 578 lifeboat radio (popularly referred to as 'Gibson Girl'). 'Gibson Girl' Crystal Radio - Schematic It consists of a baseplate, antenna tuning coil, antenna tuning capacitor and a...

A diode with a forward voltage drop as low as 0.25 V may be configured by interconnecting the base and emitter of a Germanium transistor. Basic Shunt-fed Crystal Radio It's an ideal detector for a shunt-fed crystal radio. 73, Nandu.

Diode capacitance Low capacitance diodes are a must for UHF crystal radios. It follows that they are to be so wired that the capacitance between their leads is kept to a minimum. This does not imply that the leads are to be cut to minimum length. In fact longer leads facilitate antenna-diode...

The latest update! A second Yagi Beam was then rigged up, with another diode providing the return path for the audio, instead of the coil. The signal strength was not as good. During trials, a chance shorting of the second diode gave a considerable increase in signal strength. Single-diode...

Yet another update! The terminal block arrangement made it convenient to replace the folded dipole with a full wave loop. UHF Full Wave Loop Crystal Radio Likewise with an AWX antenna. UHF AWX Antenna Crystal Radio Results were as good as with the folded dipole. 73, Nandu.

Another update. A folded dipole version, mounted on a terminal block. It obviates the need for a coil / additional diode and works quite well too. http://nandustips.blogspot.in/2015/12/uhf-crystal-radio.html 73, Nandu

Here's an update. ................Later on, another Yagi Beam was rigged up with a second OA85 providing the return path for the audio instead of the coil. UHF Yagi Beam Crystal Radio with 2 diodes - Schematic Signal strength was as good on that one too. Two UHF Yagi Beam Crystal Radios...

May be viewed at http://nandustips.blogspot.in/2015/12/uhf-crystal-radio.html 73, Nandu.

Hi Fodendaf, Why not use a water pipe earth? Or service main earth (3rd pin)? A crystal radio is much easier to build and get working than a superregenerative one. Many thanks for following. Regards, Nandu.

There's been an update. http://nandustips.blogspot.in/2015/04/unusual-crystal-radio-circuit.html 73, Nandu.

A loop antenna crystal radio is of interest, on account of its portability, though it is no match for a crystal radio using an external vertical wire antenna and earth. If it's performance could be considerably improved with increased loop size, then its portability would be the first casualty...

1. The well-known parallel-tuned, series-fed circuit. Parallel-tuned, series-fed Crystal Radio circuit. Read more at http://nandusthoughts.blogspot.in/2015/01/crystal-radio-circuits-alternative.html 73, Nandu.

Here's an update. It uses an empty lip salve stick as a tuning mechanism. Read more..... http://nandustips.blogspot.in/2015/04/permeability-tuned-crystal-radio.html 73, Nandu.

Series-tuned, Shunt-fed Crystal Radio This shunt-fed crystal radio is housed in a plastic pencil box. It has 2 windings of 30 SWG enamelled copper wire on a 6" long, 3/8 " diameter ferrite rod. Read more... http://nandustips.blogspot.in/2015/10/another-series-tuned-shunt-fed-crystal.html 73...

Here's the link. http://nandustips.blogspot.in/2015/10/another-crystal-radio-variant.html 73, Nandu.

There's been an update. http://nandustips.blogspot.in/2014/08/crystal-radio-through-speaker.html 73, Nandu.

Here's the link. http://nandustips.blogspot.in/2015/09/a-makeshift-crystal-radio-output.html 73, Nandu.