Transistor types in Bi-Pak AL60 modules?

[Tubeglow]

Originally Posted by Biggles

When I get a few minutes I'll compare your circuit with my module.

You might be able to check the (guessed resistor) with the photograph.

Yes its a bit strange..If there are any errors feel free to correct and repost.

I was thinking how to make one easily..thoughts are (other than a PCB)
use pad board with either vero pins soldered to the pads and hard wire across the top. Or plain board with turret tags and hard wire the same as the module.

Or ferric chloride and make one the same..

Originally Posted by 'LIVEWIRE?'

I traced out the circuit and drew it, but this was years ago. If I can find it I'll post it on here.

Thank's,

even the transistor numbers to update the info we have would be good.

Tubeglow.

[Tubeglow]

Originally Posted by Biggles

I think I was about 15 at the time.

I can't remember exactly how old I was I hadn't left school..I put them in a record player plinth. I wanted a Goldring turntable..but had to have a BSR at the time..

Then the later version was a complete build on a PCB (stereo and PSU) for an idea I had about going all cassette. So I bought a monolith cassette mechanism and heads then built the whole thing into a wooden chassis and bees wax polish. I had a real hard time getting the NAB EQ and gain....then got the gain and the HUMMMM.. then had to improve the regulation..then got a Dolby module from Maplins at the time..and had to up the gain again....Oh and discrete transistor bar drivers and LED's..with PCB's. Mustard caps and "tropical fish" caps were the staple fodder..(where do they get those names from..)

Ahh some happy times..
Tubeglow

[Biggles]

Bringing back memories there. I never thought I'd still be doing the same thing 35 years later! Self build was the thing in those days. I think I was the only kid in the village with a decent HiFi system. Whether it actually was decent is another matter. It sounded ok to me anyway. I was wondering what power output the AL60 actually had? I think it was marketed at about 25 Watts but as to whether it was peak or RMS I don't know. Probably about 15. Still, it was loud enough to annoy the parents and sisters. I'll have to start thinking about what pre-amp to build, although Velleman do some decent modules in both kit and ready built versions. There's also a Texan amplifier kit in progress at the moment, mentioned elsewhere on the forum.
Alan.

[Tubeglow]

Originally Posted by Biggles

I'll have to start thinking about what pre-amp to build, although Velleman do some decent modules in both kit and ready built versions. There's also a Texan amplifier kit in progress at the moment, mentioned elsewhere on the forum

Not thinking about tube then?

I use relay switched inputs with either a rotary selector or a simple stepper decade selector with a push button.
It means you haven't got to drag the signal all the way to the front of the chassis and only have to take a DC select to the coils.
Relays are Maplin BT type. Use IC sockets and plug in the relays. 1n4007 BEMF across the coils.
LED indicators.
(This sort of thing)

Tubeglow.

[Tubeglow]

Latest update.
2K change on base of BFS61

Are the ceramic caps correct?

The resistor values need checking..

Tubeglow.

[julie_m]

Originally Posted by Tubeglow

I use relay switched inputs with either a rotary selector or a simple stepper decade selector with a push button.
It means you haven't got to drag the signal all the way to the front of the chassis and only have to take a DC select to the coils.

I'll see your relays, and raise you a bunch of 4066 bilateral switches .....

[Tubeglow]

I'll keep the relays..

Tubeglow.

[Silicon]

The BFS61 is a silicon NPN with a VCB max rating of 80v.
The BFS98 is a silicon PNP with a VCB max rating of 80v.

It would be useful if you gave the transistors, resistors and capacitors numbers so that we can refer to them.
The transistor nearest the input I will call TR1. It would make sense to me if this was a PNP with its collector connected to the 33K resistor.
That would make it a voltage amplifier.
The emitter would be at the top of your diagram.
The connections of the 290R, 1.2K resistors and the 47uF capacitor don't look right to me.
Could the 290R resistor be the emitter resistor which then connects to the junction of the 47uF cap and the 1.2K resistor which are there to decouple the supply obtained from the output?

If the positive supply (VCC) is 80v DC (with reference to the negative supply) the output is usually half that. Designers often made use of it to provide a lower voltage DC supply. The decoupling eliminated the variations due to the AC signal.

The second transistor could be an NPN with its collector connected to the 12K resistor.
The third transistor could be an NPN with its emitter connected to the 10R resistor.

The BC171A is a silicon NPN with a VCB max of 45v. The emitter would be connected to the base of the BFS98.
The emitter of the BFS98 would be connected to the 10R resistor.

[Tubeglow]

Thank's,

I'll have a look at the PCB photo again tonight and check the components around TR1. I'll insert numbers for the components and insert emitter arrows we have identified so far..then repost the circuit.

Tubeglow.

[Tubeglow]

Originally Posted by Tubeglow

I'll keep the relays..

Just thought I would mention the BT relays coil must be correct polarity..ie they don't work if connected backwards. then if you have the BEMF diode soldered in you cant just change your connections over.

I use the low profile IC sockets with round pins.

Just for interest.
Tubeglow.

[Tubeglow]

This is what we have so far.

I have had a look at R6 and C7 they still look as on the diagram.
R3 could be 12K its hard to tell from the photo..

Any thoughts for transistor types for TR1/2/4..??

Tubeglow.

[Tubeglow]

Hopefully,

Biggles will be able to check the resistance values..
Or post a good picture of the component side.
Even better R1 is r2 is..

Then transistor types..need looking at..
What a pain for such a simple circuit.
(I still think its Alien Technology)..whats going on with Tr1..r6/C7
perhaps I've missed something..

NB..R18 is now linked to the output..(just in case like me you missed it)

Tubeglow.

[Biggles]

I'm making a quick copy of your diagram right now so will be taking it into work tomorrow to compare when I have a few minutes spare. Hopefully I should be able to solve one or two of the mysteries.
Alan.

[Tubeglow]

Great!..

Have fun..take some headache pills with you..

Tubeglow.

[Mooly]

BiPak I used to dream of BiPak as a youngster and can remember the adverts now.

Well I just couldn't resist having a look at this and seeing how it might perform. I suspect you need to check some of the values ( I've altered one or two) but the basic circuit architecture is correct with a classic quasi complementary output stage. Were you to build this, then you might be surprised just how good it could sound, the single ended input stage brings sonic benefits compared to the ubiquitous long tailed pair used today. The 0.22 ohm emitter resistors are virtually mandatory for reliability and bias stability but I'm not surprised the original lacks them.

[Tubeglow]

Thanks so much..

I have the feeling I know you, perhaps I'm wrong.

I will look closer at your simulation and get back.

Wow the THD is a surprise..

Is there any reason you chose 2N3055 as opposed to TIP41A?

Are the signal transistors just for the simulation or are they working real time numbers/types?
(just thinking it will save trying to find substitutions.)

Hopefully Biggles will find and post the values.

The 0.22 resistors will be a definite addition.

Tubeglow.

[Mooly]

The transistors I used are all easily available (today) and more importantly included in LTSpice's standard library.

If I were building the amp I would use 2N5551 and 2N5401 for the small signal, probably something like BD139/140 for the drivers and MJ21194's for the outputs (but in all honesty the 2N3055 are perfectly up to the job for this). The BC546 and BC560 would be fine to for the small stuff. Its all very non critical on semiconductor devices on an amp like this.

Edit... you just need the NPN's for the output. I'm that used to dealing with the complements I quoted them without thinking.

Do you want the .asc sim file to play with ?

[Tubeglow]

Originally Posted by Mooly01

Do you want the .asc sim file to play with ?

Thanks,

It's so interesting to see what I was playing with so many years ago.

Tubeglow.

[Mooly]

Here you go

[Tubeglow]

Thank's,

I wonder who designed for Bi-pak?

Tubeglow.