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From: William Sommerwerck on 9 Dec 2008 08:02
In the US, a triangle is usually a symbol for a gain stage -- most-often an
op amp. But it can also be a driver, which is likely what the triangles you
think might be transistors are.

But... I've never seen a schematic like this. Whoever drew it seems to be
using one symbol to represent different devices.

I would trace everything out, starting from the side of the transformer on
the "flat" side of the triangle. As you find parts that match the schematic
symbols, you might be able to start unscrambling the symbols' meanings.


From: DaveC on 9 Dec 2008 11:24
> repost to
> de.sci.electronics

Thanks.
--
DaveC
me(a)bogusdomain.net
This is an invalid return address
Please reply in the news group

From: bud-- on 9 Dec 2008 13:58
DaveC wrote:
> This is a partial wiring diagram for an early 80's (West) German guillotine
> paper cutter:
>
> <http://freefilehosting.net/show/42l0i>
>
> The goal of this circuit is to energize an electromagnetic clutch coil (m27)
> that takes rotational energy from a flywheel to do a task (bring down the
> knife blade). This circuit is currently not working.
>
> This machine has no ICs. There are some monolithic rectifier bridges and
> discrete transistors (the common symbol for which I cannot find *one* in the
> diagram), and plenty of passives.
>
> The transformer (m) primary center tap is connected to 24vdc. Do I interpret
> this correctly that the primary is run by a switched dc voltage? (This on a
> machine that runs on 3-phase 245vac.) Why?

Looks like the transformer must run switch-mode. The clutch is 42V while
the rest of the circuit is 24V - may be why a transformer is used.

I don't see any connection that can get to ground on the transformer
primary. Everything looks like it goes to 24+. Could be the
"Transistors?" mount on, and connect to, a grounded surface - not shown.
(That would give the "Transistors?" 4 leads.). "??" is the switch-mode
drive? Would think it also would need a ground - maybe not shown?

Where parts are about all identified it seems strange the blocks with
triangles and "??" have no identification at all.

>
> I can say from experience that other machines of this same manufacturer use a
> voltage derived directly from the 3-phase input to drive the electromagnetic
> clutch. Why use a switched voltage, I cannot understand.

The manufacturer may want all of the control to be low voltage?

>
> Is the triangle within a square symbol some sort of odd representation of a
> transistor? And the "arrow thing" that feeds them? Ideas?

My dipsiht news provider apparently no longer allows crossposting. Not
knowing which newsgroup the OP watches this is posted on all 3
newsgroups. Sorry.
From: Franc Zabkar on 9 Dec 2008 19:41
On Mon, 8 Dec 2008 23:22:17 -0800, DaveC <me(a)bogusdomain.net> put
finger to keyboard and composed:

>This is a partial wiring diagram for an early 80's (West) German guillotine
>paper cutter:
>
><http://freefilehosting.net/show/42l0i>
>
>The goal of this circuit is to energize an electromagnetic clutch coil (m27)
>that takes rotational energy from a flywheel to do a task (bring down the
>knife blade). This circuit is currently not working.
>
>This machine has no ICs. There are some monolithic rectifier bridges and
>discrete transistors (the common symbol for which I cannot find *one* in the
>diagram), and plenty of passives.
>
>The transformer (m) primary center tap is connected to 24vdc. Do I interpret
>this correctly that the primary is run by a switched dc voltage? (This on a
>machine that runs on 3-phase 245vac.) Why?

Maybe this particular clutch requires a higher frequency than 50Hz or
60Hz ???

>I can say from experience that other machines of this same manufacturer use a
>voltage derived directly from the 3-phase input to drive the electromagnetic
>clutch. Why use a switched voltage, I cannot understand.
>
>Is the triangle within a square symbol some sort of odd representation of a
>transistor? And the "arrow thing" that feeds them? Ideas?

I'd say it's probably an NPN transistor (plus associated components
?). I suspect that the rectangular block immediately above the two
chopper transistors (?) is probably an oscillator or multivibrator.

Having said that, I can't follow the current path. It appears to flow
into the transformer's centre tap and then out via either end of the
primary winding. It must then flow through the "transistors" into the
"oscillator" because the side paths are blocked by reverse biased
diodes. But the remaining terminal for the oscillator is also blocked
by diodes ...

It seems to me that your circuit is some kind of hybrid block diagram.

>Help!
>
>Thanks,


- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
From: Tim Perry on 9 Dec 2008 19:42

> Is the triangle within a square symbol some sort of odd representation of
a
> transistor? And the "arrow thing" that feeds them? Ideas?
>
> Help!
>
> Thanks,
> --
> DaveC
> me(a)bogusdomain.net
> This is an invalid return address
> Please reply in the news group
>

I believe you will find "the arrow thing" will be an astable multivibrator.

I suspect the following stage are time delay relays modules. Note they are
controlled by 24 VDC yet they are controlling AC... after all, you need AC
to run a transformer.




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