Crystal Sets

[miroflex]

Hi,

Does anyone in the forum listen to 'crystal' sets i.e. radios using germanium diodes as rectifiers? :I would be glad to hear their experiences. Even long distance reception is possible using short wave coils.

Regards.

 

[reubensm]

when i was a kid, i tried making a crystal set using an OA79 diode and a MW antenna coil. It did not work

 

[hifiashok]

hey! brings back memories.

i did, and it worked!!

 

[reubensm]

Should also mention that I used a long piece of wire tied between 2 coconut trees and a primitive pair of headphones as well. The disappointment was covered up by my father who gave me his Philips 3 band transistor radio to use after this. Would have been around 1981.

 

[miroflex]

Hello Reuben,

Nevertheless, the interest in radio continues. Incidentally, unless the headphones were of the high impedance types, the system would not work. The low impedance hi fi types are unsuitable.

Regards.

 

[reubensm]

Hello Reuben,

Nevertheless, the interest in radio continues. Incidentally, unless the headphones were of the high impedance types, the system would not work. The low impedance hi fi types are unsuitable.

Regards.

Agree 100%. We made a high impedance headphone set using the handset speakers of old telephones (dad was an engineer in BSNL). Obviously this was the problem. Could not find any such headphone model in the local market, at the time. By the way, I should also mention that I used a 500pf gang capacitor for tuning with the MW antenna coil.

Had better success later on, when I attempted to build a single transistor MW transmitter.

 

[gopib]

Agree 100%. We made a high impedance headphone set using the handset speakers of old telephones (dad was an engineer in BSNL). Obviously this was the problem. Could not find any such headphone model in the local market, at the time. By the way, I should also mention that I used a 500pf gang capacitor for tuning with the MW antenna coil.

Oh Oh, that explains it. I did the same OA79/500pf/telephone headset and so on. Now I realize the connection. My "guru" was my dad's friend who was a BSNL engineer!!! It worked !!! I still have a blue colour headset somewhere as well as a complete unit ......

 

[reubensm]

Oh Oh, that explains it. I did the same OA79/500pf/telephone headset and so on. Now I realize the connection. My "guru" was my dad's friend who was a BSNL engineer!!! It worked !!! I still have a blue colour headset somewhere as well as a complete unit ......

Most of the engineers in BSNL (Department of Telecommunications, back in the day) were into DIY so wires, components and telephone parts were available in abundance. I remember my father at times, bringing home old beat up discarded morse code transmitters to see if he could fix them.

 

[reubensm]

This is a picture of that Holland Philips Radio which my father gave me. The radio of course, is long gone...when it went dead and could not be repared because the OC-series germanium transistors were not available, we stripped it and salvaged its parts for other DIY projects.

 

[reubensm]

Hello Reuben,

Nevertheless, the interest in radio continues. Incidentally, unless the headphones were of the high impedance types, the system would not work. The low impedance hi fi types are unsuitable.

Regards.

Radio was one of my passtimes, growing up. Was very interested in DXing but did not continue as studies and career got in the way. Then, when the money came, I got down into Hi-Fi and radio took a back seat and ultimately disappeared from the agenda.

 

[captrajesh]

I made one and it worked. I made a variable air core inductor by winding laminated copper coil on to a cardboard paper pipe. In spire of the variable inductor, I'd receive only one station and the voice was very feeble. However, I was fascinated by the fact that it needed no external power.

 

[miroflex]

Hi,

Its great to know that so many of us, like me, started their DIY journey in childhood with crystal sets. I also started like this, rolling paper tubes of the right diameter, buying enamelled or double cotton covered copper wire of the right length and winding it on the paper tube or 'former' etc.

Some people also assembled short wave sets, winding coils of the required type etc. Those were wonderful days. I am thinking of getting back into this fascinating hobby.

Regards.

 

[hifiashok]

Agree 100%. We made a high impedance headphone set using the handset speakers of old telephones (dad was an engineer in BSNL). Obviously this was the problem. Could not find any such headphone model in the local market, at the time. By the way, I should also mention that I used a 500pf gang capacitor for tuning with the MW antenna coil.

Had better success later on, when I attempted to build a single transistor MW transmitter.

we called it a 'gang condenser'. also, was it 500pf (picofarad) or 'myu'f (microfarad)?

those from pune would/may remember juna bazaar from where we would try and get the discarded military, etc., mouth pieces or earphones. parts were from BP (famous for a different notoriety).

used to build what at the time were called ampli-speakers based on 555, 810S, etc., ICs (if memory serves me).

also, did some work on an electronic water level indicator, that incl. PCB design and etching/drilling!

 

[reubensm]

we called it a 'gang condenser'. also, was it 500pf (picofarad) or 'myu'f (microfarad)?

those from pune would/may remember juna bazaar from where we would try and get the discarded military, etc., mouth pieces or earphones. parts were from BP (famous for a different notoriety).

used to build what at the time were called ampli-speakers based on 555, 810S, etc., ICs (if memory serves me).

also, did some work on an electronic water level indicator, that incl. PCB design and etching/drilling!

I had done the burglar alarm using a 555 and of course, a stereo amplifier using TBA810S, and a graphic equalizer using 741...great memories!!

 

[reubensm]

Hi,

Its great to know that so many of us, like me, started their DIY journey in childhood with crystal sets. I also started like this, rolling paper tubes of the right diameter, buying enamelled or double cotton covered copper wire of the right length and winding it on the paper tube or 'former' etc.

Some people also assembled short wave sets, winding coils of the required type etc. Those were wonderful days. I am thinking of getting back into this fascinating hobby.

Regards.

Radio is indeed, a fascinating hobby...i built a shortwave set too, in those days. Of course, i did not wind my own coils (used readymade ones...I still remember using the BF series transistors, 194, 195C, 195D (if I remember correctly) with 3 IFTs...later on, I assembled a simple transmitter using an old OC71 transistor (I still remember, the circuit was from EFY Circuit Ideas back in the late 1970s, by Sandeep Baagchi)

 

[miroflex]

Radio is indeed, a fascinating hobby...i built a shortwave set too, in those days. Of course, i did not wind my own coils (used readymade ones...I still remember using the BF series transistors, 194, 195C, 195D (if I remember correctly) with 3 IFTs...later on, I assembled a simple transmitter using an old OC71 transistor (I still remember, the circuit was from EFY Circuit Ideas back in the late 1970s, by Sandeep Baagchi)

Hi Reuben,

Your post brings back vivid memories of my schooldays. I too remember using the OC71 and OC72 transistors and their cheaper Toshiba equivalents (was it 2SB77 and 2SB79?). I built a lot of small gadgets using circuit diagrams by the late Clive Sinclair, assembled on hardboard pieces drilled to accept terminals on which the parts were soldered. Etching of PCBs was a distant dream for most of us. Wonderful days ...

 

[hifiashok]

PNP.... NPN....... bbroy.......

 

[reubensm]

Hi Reuben,

Your post brings back vivid memories of my schooldays. I too remember using the OC71 and OC72 transistors and their cheaper Toshiba equivalents (was it 2SB77 and 2SB79?). I built a lot of small gadgets using circuit diagrams by the late Clive Sinclair, assembled on hardboard pieces drilled to accept terminals on which the parts were soldered. Etching of PCBs was a distant dream for most of us. Wonderful days ...

That's so nostalgic...i did the same, on old hard board pieces (dont know if you remember but back in those days, we used to get school examination boards made of the stuff, no prizes for guessing why my parents had to get me a new examination board when exams came up). Later on, started using plastic covers of pencil boxes, etc (but soldering was a challenge and had to be done carefully). This was the early 1980s (1980 to 1982). I used to fiddle around with AC125s, AC126s, OC71s, OC72s, AC127/128, AC187/188. Currently I've dug up an old project of my dad's with an AD161/162 based power amp and will be attempting to fix it (just for fun)

I used to spend hours looking at mullard amplifier circuits (valve) by a gentleman named Gilbert Davey (dont know if you've heard of him, his books used to be quite common at the British Council library)

 

[albertna]

Thanks for the nostalgic memories

 

[miroflex]

That's so nostalgic...

I used to spend hours looking at mullard amplifier circuits (valve) by a gentleman named Gilbert Davey (dont know if you've heard of him, his books used to be quite common at the British Council library)

Hi Reuben,

I seem to remember Sir Clive Sinclair and Mr Bernal Osborne more clearly. Also Mr F J Camm, whose brother Sir Sidney Camm designed the celebrated fighter plane, the Hawker Hurricane.

Regards.