A closer look at the AF108 bi-polar drive circuit

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Now here is a clearer view of the bipolar TX drive circuit, much easier to follow. Seems uncomplicated. Now to figure out just how it works.
Carl, anything to say?
I need to know what are the pulses driving this array. That's going to require modeling the timing circuitry.

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Now I will have a look at the bipolar drive circuit.......more BUY92's.....overall the two halves of the circuit are identical. I'll redraw the circuit so it can be more easily interpreted. It's time to have a look at the BUY92 data sheet in more detail. Here is the datasheet for the 1N5341 zener. And if I'm seeing right, a schottky.

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Here is the modified power supply circuit I intend to implement. I use a 555 timer as a negative voltage generator. Now somebody can tell me if this circuit can work in place of the original. I think I'll be needing a replacement for the BUY92 transistor.

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The BUY92 ist not a TUP- look in the datasheet

http://pdf.datasheetcatalog.com/data.../487271_DS.pdf

Yes, you are right. I said a medium powered general purpose PNP transistor should be OK. Not exactly a TUP. Maybe more like a BIG TUP.
I know there are some obsolete germanium type transistors lurking around in these old circuits, though the datasheet doesn't say. So I assume it is silicon type.

[Andi68]

The BUY92 ist not a TUP- look in the datasheet

http://pdf.datasheetcatalog.com/datasheets/15/487271_DS.pdf

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The BUY92 is obsolet

Hi Andi68, yes, it does appear to be an ancient PNP device, but its an ordinary jobby, nothing special, that one. Any medium powered TUP device should work, I think.
The schematic of the Whites 2000 PI shows some similarity with the AF108. Notably the power supply and the RX preamp all the way up to the second integrator. The auto-tune circuit is identical.
If your'e wondering what a TUP is, I picked up that jargon from EleKtor magazine TUP,TUN,DUG,DUS. Transistor Universal Pnp, Diode Universal Silicon, etc. They also published a list of what they considered to be "Universal" I've included it below. The PI 2000 uses a 9015 PNP transistor in the same place.

[Andi68]

The BUY92 is obsolet

[Carl-NC]

Thanks Carl,
So VC is the positive rail, U1B gain 1+(100/56)=2.8 so VC=2.8*1.2=3.34V??????
And VE is the negative rail, U1A gain 100/120=-0.8*3.34=-2.7V???????
I'm beginning to think I picked up the wrong hobby.
I guess if I spent 6 hours everyday for the next three years, I could get there. By which time I would have lost most if not all of my hair, and most likely all of my teeth from grinding away at those algebraic equations.

My numbers were guestimates, yours are probably more accurate.
And, yes, I have no hair.

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Thanks Carl,
So VC is the positive rail, U1B gain 1+(100/56)=2.8 so VC=2.8*1.2=3.34V??????
And VE is the negative rail, U1A gain 100/120=-0.8*3.34=-2.7V???????
I'm beginning to think I picked up the wrong hobby.
I guess if I spent 6 hours everyday for the next three years, I could get there. By which time I would have lost most if not all of my hair, and most likely all of my teeth from grinding away at those algebraic equations.

[Carl-NC]

Seems like you haven't seen it in ages.

Years. I think it's in a storage trailer.

Well, I think the rail voltages, although not expressly stated on the schematic, can be assumed to be +5V for VE and -5V for VC, just because of those zeners SA5's. Then V+ would be the battery voltage, here I'm assuming 12volts, and the output of the charge pump V- , which I'm going to say -12V.
V+......12V/battery positive.
VE......+5V
VC.......-5V
V-.......-12V
0V.......chassis /battery negative.
Now to design a pcb layout for the PS.
Since I don't have a SI7661/ICL7662, my charge pump inverter will instead be made using a 555 timer chip.

AD589 = 1.2V
U1B is a gain of ~3 via R5/R6 so VC ~ 3.5V
U1A is a gain of ~0.8 via R7/R8 so VE ~ -3V

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Well, I think the rail voltages, although not expressly stated on the schematic, can be assumed to be +5V for VE and -5V for VC, just because of those zeners SA5's. Then V+ would be the battery voltage, here I'm assuming 12volts, and the output of the charge pump V- , which I'm going to say -12V.
V+......12V/battery positive.
VE......+5V
VC.......-5V
V-.......-12V
0V.......chassis /battery negative.
Now to design a pcb layout for the PS.
Since I don't have a SI7661/ICL7662, my charge pump inverter will instead be made using a 555 timer chip.

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I have one of these, somewhere...

Seems like you haven't seen it in ages.

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Here is the same power supply, without the non-compulsory parts which drive the "battery alert" and "replace battery" L.E.D's
Things are becoming a bit clearer now. All that remains is to determine the actual values for the rail voltages.
Then I'll construct a stand-alone power supply for testing the main circuit. Some of those fancy diodes will be chucked out for sure!

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Here are the specs for the diodes associated with the power supply.
D4-AD589 1.2V Reference
D5,D6-SA5 Zener transient voltage suppressors
D2-schottky diode 30V, 5Amp
Interestingly, the charge pump does not appear to be synchronized or triggered, and appears isolated in this respect.
Also Battery negative is tied to the chassis box, and provides the 0V reference of the entire circuit(circuit ground).
Overall, the power supply circuit can be vastly simplified, no need for all the extras in a test circuit.

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Hold your horses, there is also a "glass passivated transient voltage suppressor" (SA12C) across the battery socket.
"Transient voltage suppressor diodes are very popular devices used to instantaneously clamp transient voltages to safe levels before they can damage a circuit."