Germanium Hi-Fi amp ??
 

Funnily enough I used to have an obscure data book on olddevices which I
gave to aan old chap some time ago. One item I recall was a silicon
replacement for germanium transistors. I thought this was impossible due to
the difference in their voltage drop, but apparently they worked well enough
at the time.

I think it was mainly for the AC series of transistors.
Brian

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"Trevor Wilson" wrote in message
...
On 10/06/2016 9:04 PM, Phil Allison wrote:
Trevor Wilson wrote:

**If you need germanium devices, Rockby have some interesting ones in
their specials list.

** I have an AD162 in my old bits box - never used a germanium type in
30 years.

**I have AD162 AND 161s in my box of bits. I needed a pair about 18 months
ago. They turn up from time to time.


Amazing those caps were all good.

** Yeah - all ELNA brand, like I used to buy from Radio Despatch in the
70s.

**As a young buck, I caught the train to RDS to bus _A_ capacitor. I was
presented with an ELNA and a (larger) Ducon. I asked for the Ducon
(because it was Aussie made). The guy behind the counter just muttered:
"The bigger the cap, the bigger the bang."



I just serviced a
3 year old M-DAC. I started marking the bad electros, until I realised
it would be easier to mark the good ones. I have to replace around 60
caps! In a DAC!


** SMD ones, I bet.

**Nope. Every one was through hole. Most had bulging tops. Funnily enough,
the M-DAC also uses 20 or so OSCON caps. I pulled a handful out and they
measured fine. Better than fine, actually. Pretty lucky, since I couldn't
source more OSCONs in the values required, unless I bought 1,000 of the
suckers. OSCONs not cheap. Also through hole types.


Too much heat during assembly allows the juice out.

**Yep. Seen it, but not in this case. Just crappy caps. Voltages on the
caps were well within reason.


--
Trevor Wilson
www.rageaudio.com.au

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Germanium Hi-Fi amp ??
 

Thermal runaway. Remember that well. R&TV Supplies in Acton did a transistor
radio kit called the elegant 7, yes a whole 7 transistors.
Trouble was almost evey component in it was a substtute for the intended
one in the original design. the single ended push/pull ciruit specified
Get 114 transistors, but the supplied ones on f dubious manufactur were
labelled S1. The radio worked for about ten mins, then started to distort
and stop. The S1 transistors got red hot. Leaving it off for a few minutes
repeated the effect. Probably not have got away with this on a mains psu.
After some poking at the company they sent us the right ones and then it
worked and still did the last time I tried it.
Goes to show tht thermal runaway can be very interesting.
No heat sink in this radio as it had a 35 ohm speaker and only gave out 500
Mw supposedly.
Brian

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"Don Pearce" wrote in message
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On Fri, 10 Jun 2016 14:50:08 +0100, "Dave Plowman (News)"
wrote:

In article ,
Phil Allison wrote:
does anyone still use germanium transistor amps - anywhere ?

Just by coincidence used one yesterday. A couple of ancient Henry's radio
kits which I put in a case with a rudimentary pre-amp many years ago. Only
10 watts per channel. The sort of thing you could leave lying around and
wouldn't get nicked. ;-)

Never did any measurements on it - but it sounded OK for the things it got
used for.

I seem to remember you had to be conservative with Germanium power
amps. Thermal runaway was always lurking just around the corner.

d

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Germanium Hi-Fi amp ??
 

On 11/06/2016 08:43, Brian Gaff wrote:

I had a Sinclair z12 amp that could put out a whole 12 watts, but although
it was not bad for crossover, it did sound kind of fluffy at times.

This one? http://rk.nvg.ntnu.no/sinclair/audio/z12.htm
What a pile of crap!

I became quite adept at fixing Z30s in my youth.
http://rk.nvg.ntnu.no/sinclair/audio/z30.htm
Maybe a much bigger heat sink would have helped
but they hardly ever survived a party.

--
Eiron.

Germanium Hi-Fi amp ??
 

Chuckle well a lot of the problem with Sinclair was that his designs fine
but when they made them they stopped at nothing to source the cheapest bits
they could to the detriment of the actual performance.
The IC amps were even worse. The IC10, was basically a power op amp with no
protection against self destruction.
The IC12, was I believe a Texas Instruments design, again with no
protection and far too much gain close to the high power parts which meant
that any supply issues were fed back to the input making it sound very bad.

The only bit of his bolt together hi fi that did work quite well was the
stereo decoder for the fm crap tuner.
I did put that on aan old tuner I had after removing the de emphasis and it
sounded very nice and low his levels, but then there was not much inside it
an a single chip was there?


Brian

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"Eiron" wrote in message
...
On 11/06/2016 08:43, Brian Gaff wrote:

I had a Sinclair z12 amp that could put out a whole 12 watts, but
although
it was not bad for crossover, it did sound kind of fluffy at times.

This one? http://rk.nvg.ntnu.no/sinclair/audio/z12.htm
What a pile of crap!

I became quite adept at fixing Z30s in my youth.
http://rk.nvg.ntnu.no/sinclair/audio/z30.htm
Maybe a much bigger heat sink would have helped
but they hardly ever survived a party.

--
Eiron.

Germanium Hi-Fi amp ??
 

In article ,
Brian Gaff wrote:
Chuckle well a lot of the problem with Sinclair was that his designs
fine but when they made them they stopped at nothing to source the
cheapest bits they could to the detriment of the actual performance.

Remember one of his pre-amps where all the pots were open frame pre-sets
with spindles attached. Not exactly built to last.

--
*Never test the depth of the water with both feet.*

Dave Plowman London SW
To e-mail, change noise into sound.

Germanium Hi-Fi amp ??
 

In article , Eiron
scribeth thus
On 11/06/2016 08:43, Brian Gaff wrote:

I had a Sinclair z12 amp that could put out a whole 12 watts, but although
it was not bad for crossover, it did sound kind of fluffy at times.

This one? http://rk.nvg.ntnu.no/sinclair/audio/z12.htm
What a pile of crap!

I became quite adept at fixing Z30s in my youth.
http://rk.nvg.ntnu.no/sinclair/audio/z30.htm
Maybe a much bigger heat sink would have helped
but they hardly ever survived a party.



From that first site......


Like many Sinclair products in the early 1960s, the Slimline relied on
the use of metal-alloy transistors rejected by Plessey for their
original purpose in early transistorized computers. However, they were
good enough for Sinclair's relatively undemanding purposes and were
either incorporated in the kits or sold as separate transistors for a
reported profit of up to 700 per cent. Sinclair's then wife, Ann, was
pressed into service to sort and test them:

"The transistors used to arrive in sacks. About three or four sacks
would arrive, about the size of a sack of potatoes. I had test equipment
consisting of a box that gave a different pitched buzz according to the
transistor, and I must have tested a million of them altogether. It
really became monotonous, because I"d no sooner finished one sack than
another would turn up."

Sinclair was certainly an early convert to industrial recycling, as one
incident shows. Texas Instruments at Bedford used a large batch of
reject transistors as hardcore for a driveway. Sinclair found out about
this, presumably through industry contacts, and rather than shrugging
his shoulders at a missed opportunity negotiated a price for digging the
whole lot up again!

--
Tony Sayer

Germanium Hi-Fi amp ??
 

Yes and his slide tuner scale was basically the same issue only in a slider
not a rotating pot.
If you replaced that with a multiturn as i did once to see if it worked, it
was miles better, but still picked up aircraft.
Brian

--
From the Sofa of Brian Gaff Reply address is active
Remember, if you don't like where I post
or what I say, you don't have to
read my posts! :-)
"Dave Plowman (News)" wrote in message
...
In article ,
Brian Gaff wrote:
Chuckle well a lot of the problem with Sinclair was that his designs
fine but when they made them they stopped at nothing to source the
cheapest bits they could to the detriment of the actual performance.

Remember one of his pre-amps where all the pots were open frame pre-sets
with spindles attached. Not exactly built to last.

--
*Never test the depth of the water with both feet.*

Dave Plowman London SW
To e-mail, change noise into sound.

Germanium Hi-Fi amp ??
 

Sounds about right. I assume you knew about the dodgy ram chips in the
Spectrum which had half the chip duff, and a link in the pcb to select the
working half only in each case.

Brian

--
From the Sofa of Brian Gaff Reply address is active
Remember, if you don't like where I post
or what I say, you don't have to
read my posts! :-)
"tony sayer" wrote in message
...
In article , Eiron
scribeth thus
On 11/06/2016 08:43, Brian Gaff wrote:

I had a Sinclair z12 amp that could put out a whole 12 watts, but
although
it was not bad for crossover, it did sound kind of fluffy at times.

This one? http://rk.nvg.ntnu.no/sinclair/audio/z12.htm
What a pile of crap!

I became quite adept at fixing Z30s in my youth.
http://rk.nvg.ntnu.no/sinclair/audio/z30.htm
Maybe a much bigger heat sink would have helped
but they hardly ever survived a party.



From that first site......


Like many Sinclair products in the early 1960s, the Slimline relied on
the use of metal-alloy transistors rejected by Plessey for their
original purpose in early transistorized computers. However, they were
good enough for Sinclair's relatively undemanding purposes and were
either incorporated in the kits or sold as separate transistors for a
reported profit of up to 700 per cent. Sinclair's then wife, Ann, was
pressed into service to sort and test them:

"The transistors used to arrive in sacks. About three or four sacks
would arrive, about the size of a sack of potatoes. I had test equipment
consisting of a box that gave a different pitched buzz according to the
transistor, and I must have tested a million of them altogether. It
really became monotonous, because I"d no sooner finished one sack than
another would turn up."

Sinclair was certainly an early convert to industrial recycling, as one
incident shows. Texas Instruments at Bedford used a large batch of
reject transistors as hardcore for a driveway. Sinclair found out about
this, presumably through industry contacts, and rather than shrugging
his shoulders at a missed opportunity negotiated a price for digging the
whole lot up again!

--
Tony Sayer

Germanium Hi-Fi amp ??
 

On 12/06/2016 12:45, Dave Plowman (News) wrote:
In article ,
Brian Gaff wrote:
Chuckle well a lot of the problem with Sinclair was that his designs
fine but when they made them they stopped at nothing to source the
cheapest bits they could to the detriment of the actual performance.

Remember one of his pre-amps where all the pots were open frame pre-sets
with spindles attached. Not exactly built to last.

Linear pots for the volume control!

--
Eiron.

Germanium Hi-Fi amp ??
 

Eiron wrote:


I became quite adept at fixing Z30s in my youth.
http://rk.nvg.ntnu.no/sinclair/audio/z30.htm
Maybe a much bigger heat sink would have helped
but they hardly ever survived a party.


** Someone gave me one Z30 module and a "Project 60" manual in the early 70s - it all sat in a drawer for several years until I figured out a use. In the manual was a schem for making the Z30 into a power sine wave oscillator using a Wein bridge circuit. See figure 4.16.1.a

http://www.epanorama.net/sff/Audio/C...oject%2060.pdf

I quickly lashed up one built to oscillate at 67Hz, with a few Hz range of adjustment. Used with an unregulated 30V supply, it ran nicely with the output feeding the 8ohm winding of a 15W UL output tranny from an old valve amplifier.

The primary was used to drive a small synchronous motor with a 240V pure sine wave. The finished version had a toggle switch to bring the frequency down to a nominal 50Hz.

This is a pretty tough job for a puny Sinclair Z30 module, but it never failed in over 20 years of use.

Who can guess what it did ?


..... Phil