Tobey & Dinsdale amp in Wireless World

DouglasSelf · 20th June 2011, 08:30 PM

I have just added some more amplifiers to the archive, including the "88-50" pre and power amps, (KT88s) and the Tobey & Dinsdale transistor amp of 1961.

The Wireless World Archive

Mooly · 21st June 2011, 11:30 AM

Interesting reading... particularly the home made transistors

Yes it is surprising no one has wanted a comeback of point contacts... now that could be a challenge ! a blameless amp made from homemade transistors.

As a youngster I remember seeing if two diodes connected "as a transistor" could be made to have any "transistor" action...

I've picked a bit more up since then though

lineup · 21st June 2011, 05:56 PM

I am working in SPICE to make a clone of the old Tobey & Dinsdale.
I think it is possible even if the original uses Germanium, I think.
I post schematic here when I get it to work..

lineup · 21st June 2011, 07:54 PM

I made my clone of Tobey & Dinsdale.
Closed Loop Gain was decreased to ~15.
Amp was compensated with 1000pF. But my cloone need only 10pF.
Amp shows rather low dist at 1 Watt 8 Ohm.
Was a nice exercise to try modernize this old antique design.

latala · 21st June 2011, 09:22 PM

I do not suppose that you have any spice models of the old germanium devices
I have often thought that a lot of modern amplifier improvement is due to better devices rather than improved design
I have built many silicon Tobey Dinsdales with good results I am a bit old fashioned and still prefer the inherent safety in capacitor coupled designs
regards Trevor

lineup · 21st June 2011, 09:27 PM

Right. The ideas they had were not all wrong.
With todays devices they can perform.

I have looked for Germanium SPICE models.
But looks as there are no working around.
At least good working.

Tekko · 21st June 2011, 09:32 PM

I suppose this is really similar to the old el cheapo posted on the ESP site, or even the same one.

20th June 2011, 08:30 PM	#1
DouglasSelf diyAudio Member Join Date: Mar 2007	Tobey & Dinsdale amp in Wireless World I have just added some more amplifiers to the archive, including the "88-50" pre and power amps, (KT88s) and the Tobey & Dinsdale transistor amp of 1961. The Wireless World Archive __________________ Douglas Self

21st June 2011, 11:30 AM	#2
Mooly diyAudio Member Join Date: Sep 2007	Interesting reading... particularly the home made transistors Yes it is surprising no one has wanted a comeback of point contacts... now that could be a challenge ! a blameless amp made from homemade transistors. As a youngster I remember seeing if two diodes connected "as a transistor" could be made to have any "transistor" action... I've picked a bit more up since then though __________________ ------------------------------------------------------- *A simulation free zone.* *Design it, build it, test it.*

21st June 2011, 05:56 PM	#3
lineup diyAudio Member Join Date: Dec 2005 Location: the north	Tobey & Dinsdale 1961 Transistor Audio Power Amplifier I am working in SPICE to make a clone of the old Tobey & Dinsdale. I think it is possible even if the original uses Germanium, I think. I post schematic here when I get it to work.. __________________ lineup

21st June 2011, 09:27 PM	#6
lineup diyAudio Member Join Date: Dec 2005 Location: the north	Right. The ideas they had were not all wrong. With todays devices they can perform. I have looked for Germanium SPICE models. But looks as there are no working around. At least good working. __________________ lineup

21st June 2011, 09:32 PM	#7
Tekko diyAudio Member Join Date: Jan 2005	I suppose this is really similar to the old el cheapo posted on the ESP site, or even the same one. __________________ The point of life is to build atleast one audio amplifier before you die.


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21st June 2011, 09:22 PM	#5
latala diyAudio Member Join Date: Feb 2006 Location: staffordshire	I do not suppose that you have any spice models of the old germanium devices I have often thought that a lot of modern amplifier improvement is due to better devices rather than improved design I have built many silicon Tobey Dinsdales with good results I am a bit old fashioned and still prefer the inherent safety in capacitor coupled designs regards Trevor

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