An electret microphone crystal set

[@thinkingjohn2099]

I built this circuit today and it worked despite not having exactly all the right components on hand but had the necessary electret microphone and did the modifications it certainly is a much better listening experience using low impedance head sets/speakers etc than the dreaded crystal earpiece

[@thinkingjohn2099]

Happy to report I built this crystal set using a 3” pvc pipe and wound quality copper insulated wire about 90 turns tapped every 10 but am mainly using total 60 turns and a lot of experimenting ended up using a switch to select sensitivity or selectively by changing the tap for the source as where I live the only 2 am statins are either less than 1km or about 10km from my home for the other I installed my coil into a 90cm storm pipe about 8 inches long and used caps on the end with one cap containing the electronics so basically it’s a cylinder that sits vertical for use, am really pleased with performance am using a telephone handset as the ear piece and wow it’s so loud and clear, I see a good earth and long wire outdoor antenna are essential btw I found when I disconnected the 1n capacitor my volume is louder for some reason

[@austinhellier7667]

Great video but no demo Peter? I built several versions of fet detector sets over the years with good success including this one. I used the Jaycar insert by cutting the track and installing a third lead to avoid soldering to the aluminium casing. I pulled in seven Brisbane locals at home and will take mine to a local park to try a long wire antenna for best results. I've also used the 3sk143 "3DQ" FET device but those ccts use an extra winding to the source of the device rather than a low Z tap. Great stuff...

[@BillyCdiy]

Hi, I made a lot of crystal radios using 3DQ, AM, SW, FM. Besides using an extra pick up coil connecting to the S-Gate of 3DQ, you can also at around 10% of the coil above the earth.

[@salimkumar1414]

Thanks

[@thomascampbell2143]

I don't see any power supply

[@manuelandrade7145]

Não é necessário

[@m005kennedy]

How long was your antenna?

[@noisyaudio]

Hi Peter, most interesting. Where did you find the three terminal mic capsule? Thanks

[@vk3ye]

Don't remember. But you can convert 2 terminal to 3 terminal but cutting the printed circuit board track on the back of the mic that joins to the metal case.

[@TechniCraftYT]

Can you use a bf256 fet instead of an microphone

[@Alex-nv7cf]

I believe.

[@janetwinslow2039]

Comparison with a germanium detector and hi-Z phones?

[@vk3ye]

I'd say about as good.

[@janetwinslow2039]

People have always been trying to make a better crystal set! Without seeing how the components in the electret mic are arranged, it's not clear how this works. Presumably there's no gain, a high impedance across the tuned circuit, and some sort of impedance transformation thorough the mic to match the low-Z phones, but how? Maybe the original article explains all...

[@austinhellier7667]

Janet Winslow the FET gate is grounded to the metal case. Cutting the track leaves the gate floating via a high megohms resistor thus allowing you to install a third lead and attach it to the top of coil.

[@gkcnalaka]

👌

[@sergiosilva6500]

It is because electret has a fet inside

[@janetwinslow2039]

Then why not just use a FET?

[@austinhellier7667]

I've used a 2N5485 in these ccts as well as the famous 3DQ FET device. There's a cut away diagram on internet showing the internal structure of the microphone capsule for those who've never peeled one open.

[@MisterClaws]

No demo of operation? Shame on you!

[@wadepatton2433]

righto---I cannot believe what I cannot hear. This is unlike Peter.

[@salimkumar9748]

Thanks