DOD 230 photocell

[kristopher612]

I was wondering if any of the photocells at futurlec are suitable replacements for the optoisolator in the schematic? Specifically I'm looking at photocell 3.  does anyone read that dark resistance as 1M?
http://www.futurlec.com/Photocells.shtml

datasheet for the clm50 shows 5K to 1M resistance. it can be viewed at http://www.alldatasheet.com/view.jsp?Searchword=CLM50&q=CLM50
any help would be greatly appreciated.  thanks so much

[JKowalski]

In my experience photocells are mostly interchangeable... Slight adjustments to the circuit may be needed in the occasional case but usually you can just stick any old photocell under the sun in and it will work well.



The LED only really makes a difference based of effeciency - a superbright will need a bigger current limiting resistor to match the response of a normal LED, for example...

If your photocell is on average a lower resistance then it should be then in your schematic you can just lower the 22k resistor in the feedback path of the second op amp to compensate, if it is too high then raise it...


By the way photcell 3 says 5000k, which equals 5meg. Photocell 10 is your best match, but it is larger. Photocell 2 would be the second best match. But like I said it doesn't really matter all THAT much.

[kristopher612]

You're right, i actually meant to type photocell 2.  good call on the photocell 10, i didn't even notice that one's light/dark characteristics.  Thanks for the second set of eyes!

[mwynwood]

I thought I'd just reply to this old post rather than creating a new one, as it's kinda along the same lines.
Necroposting?



Anyway... I'm building the DOD 230 from this vero: http://diy-layout.com/67


I'm a little bit confused how to hook up the VTL5C10 or the LED/LDR combination.
The VTL5C10 has 4 legs and I can't really see where they might go on the vero?
Is that what the green lines are about?
If I were to make my own LED/LDR combination, how would that be hooked up?
Thanks for helping out 

[mwynwood]

Like this?

[mwynwood]

Hmmm that didn't work 
Has anyone built this one?

[Ronan]

Well it looks like you put the vactrol in the right place, that's a good start. But no, I haven't built it.

[mwynwood]

Hmmm I'm still having no luck.
I took the octocoupler out and put in a red 5mm LED just to test it... and the LED stays full brightness even with no input!
That doesn't seem right...

Also, the VTL5C1 or VTL5C3 were suggested as suitable octocoupler replacements - but I've got a VTL5C10.

Help! 

[PRR]

> I'm a little bit confused how to hook up the VTL5C10 or the LED/LDR combination.

Me too. It would help to collect the Schematic. And also, since it seems to have morphed from two duals to one quad, the associated pinouts.

TRY this:



Not at ALL verified.

[mwynwood]

Hmm, no luck with that either
Thanks though! I'll try and hunt down a schematic.

Has anyone built this thing?

[PRR]

> no luck with that either

What happens? No sound?

You may have multiple problems.

Try a 5K resistor (or 10K, or jumper) at "cell". Does audio pass (constantly)?

If not, post voltages. http://www.diystompboxes.com/wiki/index.php?title=Debugging

Try a naked LED at "LED". It is supposed to be dark when silent, light when medium to loud signal is applied.

[Fender3D]

the cell should be connected at Row 1 point 13 and Row 4 point 7
LED at Row 1 point 7 and Row 2 point 7

[Ronan]

Isn't the schematic in post 1 the schematic for the vero layout, except for the IC pin numbers?

[armdnrdy]

Ronan,
To answer your question,

"Isn't the schematic in post 1 the schematic for the vero layout, except for the IC pin numbers?"

Yes it is. I've looked at this a few times trying to help but it's a bit more work when the schematic has the values listed, the layout has the component designations listed, and the schematic and the layout do not match due to the retrofit of a quad op amp from two dual op amps.

[mwynwood]

the cell should be connected at Row 1 point 13 and Row 4 point 7
LED at Row 1 point 7 and Row 2 point 7

Hmm so, like this:

That's how I've got it, so it must be something else... I'll keep troubleshooting

[Ronan]

Ronan,
To answer your question,

"Isn't the schematic in post 1 the schematic for the vero layout, except for the IC pin numbers?"

Yes it is. I've looked at this a few times trying to help but it's a bit more work when the schematic has the values listed, the layout has the component designations listed, and the schematic and the layout do not match due to the retrofit of a quad op amp from two dual op amps.

Fair enough, I'm having the same problem. Can't relate the vero to the schem since there are no values for the vero. It then becomes a crossword puzzle that I don't need. Just wanted to confirm that was the correct schematic.

Next question is, Marcus, how did you know what value components to fit to the vero, since the values are not listed, or am I missing something?

If the LED is on all the time, with or without input signal, then the output is high (pin 7 of the LM358 in the schematic). The output state depends on the difference in voltages at pin 5 and pin 6. The voltage at pin 6 is controlled by the transistor, when the transistor is off, pin 6 should be close to 9V, and pin 7 should be low, turning the LED off. That is, with no input signal, pin 6 should be close to 9V, and pin 5 should be around 3V.

[mwynwood]

This is what I've been going off:

http://diy-layout.com/67

[Ronan]

Marcus, I think that vero layout has errors.
R12 looks correct, but R13 should connect from R12 to ground (row 7 to row 10 instead of 7 to 9). Then R11 has to somehow connect to the TL074 pin 5 to pin 7. I don't think this was ever verified.

Edit - I would start with those changes, and it might work, if not, let us know. If it does work, let us know too

[mwynwood]

Marcus, I think that vero layout has errors.
R12 looks correct, but R13 should connect from R12 to ground (row 7 to row 10 instead of 7 to 9). Then R11 has to somehow connect to the TL074 pin 5 to pin 7. I don't think this was ever verified.

Edit - I would start with those changes, and it might work, if not, let us know. If it does work, let us know too

I just made those changes with no luck
When I puck a resistor where the CELL should be, The LED stays on no matter what all the time.

[armdnrdy]

Marcus,

Have you ever etched your own boards? If you search the net there is a PCB available that includes all of the relevant information.


Looking at your first post in this thread, I see that you've been trying to get this thing going since May 2012. That's quite a long time for a small, easy build such as this.

You just had two very knowledgeable people (PRR and Fender3D) roll through here trying to help you, and they couldn't get it with the information supplied.

A bit of advice: Sometimes when I get the information to a project, it will not be in the optimum format. First thing I do is fix that.

Let's say as in this project the info is all there but not consistent from schematic to layout to bill of materials. (BOM) What I would do is trace the circuit out adding the missing info, component designations (numbers) to the schematic. Print out the schematic and go through the layout penciling in the component designations as you go.

Google the data sheet for the TLO74 to get the proper pinout and use the available info to:
A. Verify the TLO74 vero build
B. Verify where the VTL5C10 goes in the circuit.

If you need any more help, there are many members of this site that are very generous with their time and would be glad to help you.