1952 - Build your own Transistor Radio - UK Vintage Radio Repair and Restoration Discussion Forum

itactics · 12th Apr 2010, 8:29 pm

This interesting article predates the release of the worlds first transistor radio, the Regency TR-1, by two years!

http://www.jamesbutters.com/buildatransistorradio.htm

David G4EBT · 12th Apr 2010, 9:05 pm

Very interesting James - I wonder how many people took the gamble and forked out $6.50 each for three point contact transistors, and whether their gamble paid off!

I remember in my teens in the mid 1950s, surplus 'red spot' and 'white spot' transistors costing ten shillings - a tidy sum in those days, and more than most valves. Bascially, these were out of spec transistors offloaded onto the surplus market with no maker's ID marks.

Red spot were audio - white spot (allegedly!) were good for RF. All very hit and miss - you either got lucky and they worked, or unlucky, and blamed yourself for killing these three legged fuses.

Ah yes, I remember it well!

David,
G4EBT

itactics · 12th Apr 2010, 11:59 pm

And David, if their gamble paid off I wonder if any survive today?

David G4EBT · 13th Apr 2010, 10:07 am

I'm sure they do - I have a few! I see them as testimony to my having a low gullibiblty threshold in parting with hard-earned cash as an impoverished apprentice in the late 1950s.

The extreme variabilty of 'red spot' surplus transistors meant that it was a gamble as to whther or not they worked at all - be it as oscillators, amplifiers, at AF or RF. I've unearthed a few out of my spares box and tested them. (We didn't have the means back then to test them accurately of course).

The results are shown in the pics, and as can be seen, the gain ranges from as little as 5 to as much as 90, which shows the extent of variabilty. Those four will have cost me £2.00 altogether at the time (1958/9) - about a quarter of a week's wage as a senior apprentice.

At least those transistors do still do work after more than fifty years!

David,
G4EBT

Herald1360 · 13th Apr 2010, 12:25 pm

The first device looks exactly like what was in a Repanco amplified crystal set my brother had in the early 60's. Never seen similar since (until now....)

I wonder if anyone recognises the package?

fidobsa · 14th Apr 2010, 7:40 am

That's a neat little transistor tester. I have one somewhere I made back in the mid '70s using a Colmans mustard tin as the case and a tape recorder vu meter for the gain readings!

FRANK.C · 14th Apr 2010, 8:50 am

The battery voltage appears very high in that article at 45 Volts.
I haven't seen a transistor radio with a battery voltage that high before. Would it be a misprint and should read 4.5V?

Frank

Darren-UK · 14th Apr 2010, 12:30 pm

I don't know, the Regency TR1 used a 22½V battery and that was a diddy little radio. This project is, by the standards we know today, very bulky so 45V possibly isn't as ludicrous as it may seem.

Also, the project is hardly what you'd call a portable or personal radio so the physical size of the battery wouldn't be a concern - up to a point anyway. I once had a little Emerson hybrid effort that could just about be called a 'coat pocket' radio and that used a 45V battery, so such batteries did exist.

David G4EBT · 14th Apr 2010, 10:08 pm

Quote:

Originally Posted by fidobsa

That's a neat little transistor tester. I have one somewhere I made back in the mid '70s using a Colmans mustard tin as the case and a tape recorder vu meter for the gain readings!

I've appended a couple of pics of testers I made long ago - one, for PNP/NPN, in 1970 - (yikes, 40 years ago!) - the other, for FETs, in the 1980s. They're looking a bit sorry for themselves, with their yellowing front panels, but they work well enough and were in constant use until one of my sons bought me the posh tester about five years ago as a birthday present.

Bless!

David.

12th Apr 2010, 8:29 pm	#1
itactics Retired Dormant Member Join Date: Jul 2007 Location: Christchurch New Zealand Posts: 96	1952 - Build your own Transistor Radio This interesting article predates the release of the worlds first transistor radio, the Regency TR-1, by two years! http://www.jamesbutters.com/buildatransistorradio.htm

12th Apr 2010, 9:05 pm	#2
David G4EBT Dekatron Join Date: Feb 2003 Location: Cottingham, East Yorkshire, UK. Posts: 5,761	Re: 1952 - Build your own Transistor Radio Very interesting James - I wonder how many people took the gamble and forked out $6.50 each for three point contact transistors, and whether their gamble paid off! I remember in my teens in the mid 1950s, surplus 'red spot' and 'white spot' transistors costing ten shillings - a tidy sum in those days, and more than most valves. Bascially, these were out of spec transistors offloaded onto the surplus market with no maker's ID marks. Red spot were audio - white spot (allegedly!) were good for RF. All very hit and miss - you either got lucky and they worked, or unlucky, and blamed yourself for killing these three legged fuses. Ah yes, I remember it well! David, G4EBT

12th Apr 2010, 11:59 pm	#3
itactics Retired Dormant Member Join Date: Jul 2007 Location: Christchurch New Zealand Posts: 96	Re: 1952 - Build your own Transistor Radio And David, if their gamble paid off I wonder if any survive today?

13th Apr 2010, 10:07 am	#4
David G4EBT Dekatron Join Date: Feb 2003 Location: Cottingham, East Yorkshire, UK. Posts: 5,761	Re: 1952 - Build your own Transistor Radio I'm sure they do - I have a few! I see them as testimony to my having a low gullibiblty threshold in parting with hard-earned cash as an impoverished apprentice in the late 1950s. The extreme variabilty of 'red spot' surplus transistors meant that it was a gamble as to whther or not they worked at all - be it as oscillators, amplifiers, at AF or RF. I've unearthed a few out of my spares box and tested them. (We didn't have the means back then to test them accurately of course). The results are shown in the pics, and as can be seen, the gain ranges from as little as 5 to as much as 90, which shows the extent of variabilty. Those four will have cost me £2.00 altogether at the time (1958/9) - about a quarter of a week's wage as a senior apprentice. At least those transistors do still do work after more than fifty years! David, G4EBT Attached Thumbnails

13th Apr 2010, 12:25 pm	#5
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: 1952 - Build your own Transistor Radio The first device looks exactly like what was in a Repanco amplified crystal set my brother had in the early 60's. Never seen similar since (until now....) I wonder if anyone recognises the package? __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

14th Apr 2010, 7:40 am	#6
fidobsa Retired Dormant Member Join Date: Mar 2009 Location: Zala, Hungary Posts: 418	Re: 1952 - Build your own Transistor Radio That's a neat little transistor tester. I have one somewhere I made back in the mid '70s using a Colmans mustard tin as the case and a tape recorder vu meter for the gain readings!

14th Apr 2010, 8:50 am	#7
FRANK.C Heptode Join Date: Feb 2006 Location: Roscommon, Ireland Posts: 732	Re: 1952 - Build your own Transistor Radio The battery voltage appears very high in that article at 45 Volts. I haven't seen a transistor radio with a battery voltage that high before. Would it be a misprint and should read 4.5V? Frank

14th Apr 2010, 12:30 pm	#8
Darren-UK Retired Dormant Member Join Date: Apr 2003 Location: Blackpool, Lancashire, UK. Posts: 4,061	Re: 1952 - Build your own Transistor Radio I don't know, the Regency TR1 used a 22½V battery and that was a diddy little radio. This project is, by the standards we know today, very bulky so 45V possibly isn't as ludicrous as it may seem. Also, the project is hardly what you'd call a portable or personal radio so the physical size of the battery wouldn't be a concern - up to a point anyway. I once had a little Emerson hybrid effort that could just about be called a 'coat pocket' radio and that used a 45V battery, so such batteries did exist.