Amplifier box

schombi

Would one of you have more information on this amplifier box (if it is one)?


Who was the manufacturer, what exactly was the purpose, is there a manual and how was it connected? The box has a power plug style plug and a 3.5mm audio plug, where on the box itself it has female connectors for both. Maybe it?s because of the public holiday we have today where I could stay in bed longer, but I?m a little confused by the box. Don?t want to fry one of my Speccys.

roko

It is not professional, unless what I see as the power-in plug, is in fact power-out. ( I do not believe there is some internal battery :-).
No doubt it is an audio amp, but you'll have to open it up to deduct the plus and minus of the power, and to see what is input and output.

schombi

Thanks! I opened it up and took a photo of the innards. Hmm, nothing printed on the PCB.



Larger photos can be found on:
http://schombi.de/public.html

joefish

My guess would be you're meant to plug the Speccy power supply into it, then plug it's lead into the Speccy - so it leaches power from the Sinclair PSU. Not really a great idea.

You then plug the audio lead into the EAR socket and connect it to your Hi-Fi via the jack socket. I'm not sure I'd trust to use it myself.

Looks like a printed circuit board, but a standard off-the-shelf project box, so maybe it was one of those things sold as a hobby kit, perhaps through an electronics mag?

ingo

It might be an "amplifier" for amplification of weak tape signals to use for "LOAD"ing into the Spectrum. But it is a simple solution I would not use. It uses a digital gate circuit for analog purpose. One can do that but as there are a lot of good analog circuits available I would prefer a better solution. Nothing is printed on the PCB and there is no cord grip. Roko will be right, it seems not to be a commercial product.

Ingo.

schombi

Thanks for your inputs. I?ll leave it off a real Spectrum then and keep it as a "display unit".

Pluto63

Actually it's a light-pen interface, I do have one similar in a red box and you are missing the light-pen itself that goes on the female plug on the box. The power supply of the spectrum goes to the box. It's a home made kit that was sold in the old days.

schombi

You could be right, Pluto63. In the crate, where I found the box, there was also an unlabeled light-pen with an audio plug of the same style!

But, what the heck is the potentiometer for then??? Which software was used with it and how did it work? All other light-pens I?ve seen so far, required a real interface to be connected to the expansion port.

Pluto63

Pontetiometer is used to tune the pen for the screen, and I must have the software tape and the manual somewhere, if interested I could go hunt it.

joefish

Ahh, you'll set the brightness level at which the pen flips from reading dark to light. Sounds interesting. I used to have a light gun for a Grandstand console, which was fun. Even if it's just hitting a single flashed bright target rather than actually trying to track the gun's position.