Narrow-Bandwidth Television Association

gary wrote:Well at least you seem to be able to produce these boards quickly - good luck with that one.

The circuit mark 2 has come and gone ! it was amplifying but not with the solar cell for some reason ...

So another step back to go forward so i am scratch building it...

As i said i must of killed the first solar cell i know i had a short when some solder hit the sensor while on ,i still have one good one and the dead one i have taken the lens off and put it on a LDR ...i have made an amplifying circuit that works with that LDR now but i want the have the solar cell going as well i want to try and make that tonight ....

I want to see if i can make it so i can switch between the LDR and solar cell to see the difference if any, but so far i have learned amplifying a solar cell is harder for me than an LDR well trying via copying the circuits in the newsletters more than likely my fault ,but i will not stop till i do it i will not let an amplifier beat me Gary

Harry, would it be possible for you to build the circuit on a breadboard? That way we would have a chance of helping you debug it.

Both the circuits you have tried are pretty much tried and proven circuits but because they are such high gain it doesn't take much to get them to misbehave.

On my FSS lash up I just implemented a simple two stage transistor circuit which amplified it just enough to get it into my PC where I could process the signal further. If you are happy to just emulate my paltry efforts you could try that method.

gary wrote:Harry, would it be possible for you to build the circuit on a breadboard? That way we would have a chance of helping you debug it.

Both the circuits you have tried are pretty much tried and proven circuits but because they are such high gain it doesn't take much to get them to misbehave.

On my FSS lash up I just implemented a simple two stage transistor circuit which amplified it just enough to get it into my PC where I could process the signal further. If you are happy to just emulate my paltry efforts you could try that method.

Hi Gary

You know i was just looking for my bread board !

I found this i think lawnboy posted a few years ago i like the bc109 2 transistor one might be similar to yours.
i also like the lm386 one in this post for a try but knowing that ic its is a bit noisy ...
Ok i will bread board see how i go with this transistor one.
Yes i have no problems copying Gary your help here is priceless so i will never say no to help.

I don't think that will provide anywhere near enough gain Harry.

gary wrote:I don't think that will provide anywhere near enough gain Harry.

Which one Gary the lm386...?

yes sorry, for the low level of light that these sensors have available to them you need a gain of several hundreds - the LM386 provides something like 30 IIRC.

gary wrote:yes sorry, for the low level of light that these sensors have available to them you need a gain of several hundreds - the LM386 provides something like 30 IIRC.

Gary the circuit with the 2 Bc109 transistor is looking good.

just waving my hand in front of the dome sensor in room light i can see this happening on my scope..so this is good .

Also i can see its picking up the light movement from the tv across the room.

Sorry Harry - I didn't notice the second circuit - yes that is similar to mine but with more feedback - it should work fine. Keep in mind that these simpler circuits probably won't have the overall performance of the more complex circuits but they should be adequate for your experiments.

gary wrote:Sorry Harry - I didn't notice the second circuit - yes that is similar to mine but with more feedback - it should work fine. Keep in mind that these simpler circuits probably won't have the overall performance of the more complex circuits but they should be adequate for your experiments.

Its more sensitive than i was thinking it could do ,i was very happy it picked up the television might very well pick up that nipkow .

Okay i will give it a shot with this circuit ,i might try and see what another stage will do but i will solder this one .

So this sounds like it would be fine to record ,i just need this to also via another amplifer to drive my luxeon for the little monitor,i made the club circuit for this but seeing this now i can see i should have done this part simpler so i might rethink this part of it .

Today i finished version 3 of the circuit ,last one worked but when i soldered it up i got nothing and after some fault finding and while ripping parts out i found it was a cracked copper strip causing my grief .....

So i gave the circuit at the top of my last circuit post a go since the last one was half gone after fault finding.the 3 transistor BC109 one ,i am using BC 108s and was working on the breadboard and it now also works on the soldered version ....at last what a pain .

Since i had a damaged dome sense i replaced the sensor with a LDR i wouldn't mind seeing the difference between the solar cell later and it , i have a transistor circuit that works with it but got to keep it simple for now,theres a good read perhaps only one on a LDR camera system in issue 21 ,1 of the newsletter.

Heres there ldr circuit i tried that works with my ldr but i tried a 100k for the fixed resister and a 10k for the pot... same transistor but so looks like its pretty easy one to get right.

I have added a adjustable voltage regulator to it runs off 7 volts in the circuit drawing ..in the picture i think i have it on 3 or 4 volts which is way down at what it can do but it still picks up the televison ,doesn't show it well on a still photo but its pretty good with the room light.

BTW it takes a few seconds to work once powered up i recall Steve saying this in a post to lawnboys go at a Head amp.

To day i mounted the light and the luxeon for the monitor and after all the trouble i had with the light sensor circuit time to play around with the lens.

I found either moving the disk back with all the mounting stuff or move the lens forward lets me drop the light dot size but it does also drop the scan size ,i am sort of happy with that distance of cause went for the easier way with the lens .

I think i could keep that distance and and drop the light dot size again if i work at a better nipkow with a smaller hole.

Some thing i noticed thats rather interesting passing the light passed the nipkow hole on the dvd is its refracted along the edge of the dvd like a beam splitter.....this looks interesting if you made a stack of dvds you could make a dvd mirror screw or on the flat theres a light line that could also be used to make a montor of some sort .

See pictures you may notice it in the pictures ,,,in any case the project moves on and more work tonight .

Excellent work Harry!

First thing I look at each morning is your progress.

Your construction quality is to be admired!!

Kind regards,


Graham

AncientBrit wrote:Excellent work Harry!

First thing I look at each morning is your progress.

Your construction quality is to be admired!!

Kind regards,


Graham

Hi Graham

Thanks i think it looks ok i think i should be able to get at least something with it ,i have never tried a flying spot camera before so a lot of help from gary here ,i just wanted to try and make it smallish so thats my take on it .

This is where i am putting the sensors...the solar cell one for the start..

I am going to get the monitor going tonight ,i may need another amp between the light sensor circuit and luxeon circuit ,the light box looks like it works great ....the picture will be side on i think where i placed the light box .

More to come let you know how i go .

That thing looks freaken beast!

Hopefully it'll work without a hitch

Looks a bit like him: