Questions About Construction Of The Australian Mystery Crystal Set

I've been looking at a number of simple crystal radio designs, and I've found the Australian mystery crystal set, and am interested in building that, mainly because it's an Australian design, and I've heard it it's a pretty good performer. I only have 2 questions- can I substitute the detector for a 1N34? and what is double silk covered wire and do I really have use that? What's wrong with regular coil wire? I can only find 23 SWG, 25 SWG, and 33 SWG where I need 24 SWG,

30 SWG.

Thanks

Dave

Reply to
Dave.H
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Forgot to give the schematic

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Reply to
Dave.H

It's wire insulated with silk.

Not unless you want it to be 'period authentic'.

Graham

Reply to
Eeyore

Not really, I'm building it on a metal chassis (coil mounted above, vertically) and don't really care about vintage looks. I can't seem to find wire of the right diameter, though, that's the only part I've yet to find.

Reply to
Dave.H

That's a great looking radio.

Use 23 or 25 or whatever is handy. The significant difference between cotton covered and enamel covered wires is that cotton spaces the wires a little farther apart than will the enamel, and it will take slightly more cotton covered wire to lay on the same number of turns as the enamel wire. Bottom line is, the two coils would have slightly difference inductive reactance. The turns count is probably a swag anyhow, and it's the reason most xtal sets using wound coils, put on lots of turns with taps so the range of tuning can be easily changed (hint, hint).

I don't know what a really good replacement for the 1N34 would be. I'd look for a Hot Carrier diode if nobody comes up with a part number. From an occasionally defective memory, I think the 1N82 may be one.

Reply to
Don Bowey

"Donald Duck Bowey"

** Try reading the damn question - f****it.

....... Phil

Reply to
Phil Allison

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Read that, it's interesing., don't know if it'll help you how ever. I'm guessing that if you used enamel wire you would be fine for what you're doing.

--
http://webpages.charter.net/jamie_5"
Reply to
Jamie

Sorry grampa. I'll try to do better next time.

If you keep using those naughty words I'm going to tell on you.

Reply to
Don Bowey

You can use regular coil wire of whatever size you can get that is close, and the 1N34 is fine as the detector.

Ed

Reply to
ehsjr

You might do rather well with a zero bias schottky diode.

Failing that, any germamium point-contact type (like the 1N34) would be a decent sub.

Graham

Reply to
Eeyore

I'll go with the 1N34. I'm also going to install a 1S5 tube as a second detector, switchable between the two, with a 'D' cell powering the filament.

Reply to
Dave.H

Hi Dave, I almost feel bad giving you this URL, it is so full of useful information that it may be a while before you have time to get anything done. See section 1. Out of the 29 atricles, I think 5 or 6 are about how to improve the diode/detector operation. Oh, and see #19, Ben discusses the 1932 "Mystery Crystal Radio"

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Have fun, Mike

*and what's this stuff about a D cell on a crystal radio :-)
Reply to
amdx

Gack! How about using a transistor (base -emitter of PN3904 connect B to coil, E to phones), and a 1k resistor from the collector to battery (+)? Battery (-) to ground.

Or go low-tech and use a two-potato battery.

Reply to
whit3rd
*and what's this stuff about a D cell on a crystal radio :-)

I got the idea from one of Dave Schmarder's radios, #26

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Reply to
Dave.H

Hi Dave, My point was, the purists would shudder at the thought of an external power source on a crystal radio. Now if you extract the power from a strong local and use that to amplify a weak signal then your doing good work. Mike

Reply to
amdx

A metal chassis can influence performance very much, because metal in front of a coil acts as a shorted winding. I advise to test things without a chassis, on a non-metal table surface, and when it performs as intended, try it in your metal housing. I would choose a wooden or plastic box however.

Reply to
Sjouke Burry

The tube isn't being used as an amplifier, it's diode is used as a switchable option to a SS diode. The battery is for it's filament.

Reply to
Don Bowey

Ok then, the purists would shudder at the thought of an external power source on a crystal radio. Now if you extract the power from a strong local and use that to bias your diode then your doing good work. Gees Don, your acting like Phil but without the name calling :-) Mike

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Reply to
amdx

Substitutes will work fine. All the other stuff is to make it look like a "period piece." Go to a rock shop and get some galena for the detector if you want to go retro.

Steve.

--
Steven D. Swift, novatech@eskimo.com, http://www.novatech-instr.com
NOVATECH INSTRUMENTS, INC.      P.O. Box 55997
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Reply to
Steven Swift

Geez Mike, why didn't you take time to see what the OP was doing?

If you wish to really be a purist you should insist one should use a coherer for the detector, or a chunk of galena and a cats-whisker.

I think it's a bit cool to have two different detectors and be able to switch between them, like in the good old days.

Reply to
Don Bowey

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