Some of the higher power amps of that era used a pair of the same transistors in the output, with a driver transformer, dual secondaries each driving a base with opposite polarity. The primary was driven thru a blocking capacitor, to keep DC out of the transformer for best linearity. I think the Pilot and Acoustic Research amps used this method. At higher power, the bias stability was of a concern, so using a low resistance secondary winding helped a lot. Of course they had some kind of thermal compensation such as a NTC thermistor. Also, using a transformer prevented blown output transistors from taking the driver(s) with them.
I seem to recall that the driver's seat would slide all the way back until it touched the rear seats.
The French USED TO BE our friends.
My father-in-law-to-be ran a machine shop. He took a big piece of
1/2" aluminum and machined me a perfect mounting surface depression with perfectly aligned holes.
About the same time I discovered that my wife-to-be knew how to work on car transmissions ;-)
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
X-No-Archive: yes "Watson A.Name - wrote : "Jim Thompson" wrote : > "Tam/WB2TT" wrote : > >"Jim Thompson" wrote : > >> Stumbled onto the following URL... :
roject : s_Penfield_MiniAmp.htm : > >>
:>>> This is personally hilarious to me since Paul Penfield was one of my :>>>(very excellent) instructors at MIT... but he taught field theory at :>>> the time... I didn't know he had dabbled in audio. :>>> ...Jim Thompson
: > >Jim, : > >Genuinely odd. I have never seen an amp of that era before that did : not use : > >a transformer coupled speaker. Wonder if these speakers were : originally : > >special built to handle the DC, and also higher impedance. 40 Ohms : comes to : > >mind. I notice the volume control is connected in a conventional : manner; : > >didn't they use to turn it around because of the relatively low base : input : > >impedance? : > >
: > >I have a 1962 Lafayette Electronics catalog. Sometimes fun to look : at. : > >
: > >B&G Merlot, 2002. 1.5L for 10.99 : > >
: > >Tam : > >
: >
: > Back then I built a class-A amplifier for my '61 Renault Dauphine : > using one of those Delco door-knob Ge power devices. I used a choke : > load and capacitively coupled to the speaker. Actually sounded pretty : > decent. : >
: > ...Jim Thompson : > -- : : Back in high school, I knew a guy who had a Renault Dauphine and he was : 6 foot 8. I could never figure that out. Today most people wouldn't be : caught dead with a French car. Next to the Yugo... : : The Delco 2N278 TO-36 on a big heatsink, and a big choke were standard : on the back of those GM radios of those years. I replaced quite a few : of those transistors, got a lot of white silicone goop on my hands. : Screwed up an occasional mica washer, too. : : I hated to work on Caddy radios because of all the air conditioning : ducts that were in the way. Since it was a class A circuit, with heavy : collector current, the germanium transistors tended to get out of hand : when the environment get hot. Did you notice in the schematic in the : URL above, that the DC was also across the headphones? I don't think : I'd like to have DC thru a pair of headphones, they might singe my ears! : Someone should've put a 1000 uF cap in series with the headphone jack.
The Renault was really cheap. They cost about $1200 which would be about $8,000 today. A lot of people thought a scooter would save them money! LOL
My experience with Ge Transistors was mostly 2N441 "door Knobs" with 2N465 drivers. We made 1KW frequency changers for driving aircraft equipment in a test lab. Among other power and signal equipment with Ge PNP simi-conductors predominant. You know
2N404, 2N1302,4,6 etc. Some systems used thousands of 2N404's and
2N1302's. With a cabinet as big as a coffin!
I and my friends burned out a lot of those doorknob transistors and the
2N458As, too. We used to make DC-AC inverters that ran at over 400 Hz. We used a Tek 541 or was it 531 'scope for a load because the power transformer would handle those higher freqs. Took over 250W to run that 'scope. Later we used the inverter to power our mobile stereo amp.
: > The Renault was really cheap. They cost about $1200 which would be : > about $8,000 today. A lot of people thought a scooter would save : > them money! LOL : >
: > My experience with Ge Transistors was mostly 2N441 "door Knobs" : > with 2N465 drivers. We made 1KW frequency changers for driving : > aircraft equipment in a test lab. : : I and my friends burned out a lot of those doorknob transistors and the : 2N458As, too. We used to make DC-AC inverters that ran at over
400 Hz. : We used a Tek 541 or was it 531 'scope for a load because the power : transformer would handle those higher freqs. Took over 250W to run that : 'scope. Later we used the inverter to power our mobile stereo amp.
The FChangers were 60 hertz input (CPS back then) to 400 hertz modified Sine out. Used a 40 Volts intermediate DC level. We had to hold plus-minus 10 Hertz. Never heard of power being THAT fussy, but some of the gear was motor driven, like DRUM memories.
: > Among other power and signal : > equipment with Ge PNP simi-conductors predominant. You know : > 2N404, 2N1302,4,6 etc. Some systems used thousands of 2N404's and : > 2N1302's. With a cabinet as big as a coffin! : : Sounds like it was military equipment.
Most of it... Some for NASA too. Range equipment and some that had to run at -20 degrees C, to 45 Degrees C, cool area stuff on a mountain top!
On the other hand the ADC's and Data Mux for the X15 was tiny by comparison. Only about thirty cubic inches. (Its on display in the Dayton Ohio Air and Space Museum if your ever in that area.) The Rocket telemetry gear was also pretty small. For then!
IIRC my 1961 Dauphine cost me $1100.00, purchased at Luby Chevrolet in Boston.
...Jim Thompson
-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |
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| 1962 | I love to cook with wine. Sometimes I even put it in the food.
My high school French teacher (who else?) had a Dauphine. As a practical joke, the school jocks picked it up and turned it 90° in its parking spot one day.
Some Cambridge "urchins" (Win will appreciate the term) picked mine up out of the street and placed it on the sidewalk end-to-end between two trees :-(
With only inches to spare I jockeyed it back and forth for probably 20 minutes before I got it free.
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
I only saw one launch at white sands, the top stage was an AEROBEE I have no idea what the other two stages were. I was there to supervise the installation of our telemetry gear in the AEROBEE but they let me hang around for the launch. They said "two, one, zero" and the assembly lifted off, seconds later it was out of sight. But the telemetry came in just fine. I have no idea what the mission was, or the result. Part of a upper atmosphere analysis I was told. The third stage peaked at over seventy miles. Like I said, only a toy!
I attended a college that had a very small female undergraduate population (about 50/2500). Most of the single girls lived in an old mansion on the college grounds in the midst of several male-only dormitories. One Saturday night several young men (identities unknown to me) picked up a samll English sports car (Austin?) and carried it up a half-flight of stairs onto the mansion porch. The girls had the last laugh - they pushed the car in through the double front doors and "hid" it in the grand hall.
I prefer the MIT hack at a Harvard football game myself....
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...Jim Thompson
-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |
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| 1962 | I love to cook with wine. Sometimes I even put it in the food.
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