Another LERA question

[danielzink]

Hey all,

I've built a LERA:



It works - as in - if I put an ohmmeter on the output jack - I can read "ramping"
The ohms go up and down - unfortunately it's pretty fast - there doesn't seems to be much adjustment it ramps right up and right down. The electro is discharging at a pretty slow rate - but the rate at the jack is fast fast - no matter where I set the pots.

secondly - I'd like to use it on my Effectrode Tube vibe. The Vibe has an "expression pedal" input jack - but the LERA didn't do anything when plugged in.
Then I stumbled upon this diagram with regards to the vibe:



I'm a bit confused.

The first paragraph states a passive volume pedal can act as a speed controller - isn't that what the output jack of the LERA should be doing ?


Or....Do I need to make 5V on the ring of the jack ?

Thanks for any help.

Dan

[danielzink]

well....after sitting around all day trying to cipher this thing....I make a post and 10 seconds later.....I think I've figured it out.....

Do I need a stereo output jack on the LERA....with the Sleeve and Ring connected together ?...........


the vibe needs to see a stereo jack 'eh ?

[R.G.]

there doesn't seems to be much adjustment it ramps right up and right down. The electro is discharging at a pretty slow rate - but the rate at the jack is fast fast - no matter where I set the pots.

What you're telling me, put another way, is that the opamp output pin, pin 1, is not following the electro cap, right? Why could that be?

secondly - I'd like to use it on my Effectrode Tube vibe. The Vibe has an "expression pedal" input jack - but the LERA didn't do anything when plugged in.  Then I stumbled upon this diagram with regards to the vibe:

Link to the ETV schemo?

[danielzink]

there doesn't seems to be much adjustment it ramps right up and right down. The electro is discharging at a pretty slow rate - but the rate at the jack is fast fast - no matter where I set the pots.

What you're telling me, put another way, is that the opamp output pin, pin 1, is not following the electro cap, right? Why could that be?

secondly - I'd like to use it on my Effectrode Tube vibe. The Vibe has an "expression pedal" input jack - but the LERA didn't do anything when plugged in.  Then I stumbled upon this diagram with regards to the vibe:

Link to the ETV schemo?

Ramping is fine - my mistake.

ETV schemo ? not likely....I've looked everywhere.


Anyhow - onward and upward.

I cobbled this up and it works:

So how do we configure the LERA to act the same way ?

[danielzink]

Okay - got it sorted - that it will control the speed on the 'Vibe.

Seems the sheild and tip carry signal.

Now - it can't get it to go slow enough ? the lowest resistance I can get is 10k and it's still whippin' fast.

RG ? any ideas on how to make it go slower ?

Thanks, Dan

[R.G.]

Okay - got it sorted - that it will control the speed on the 'Vibe. Seems the sheild and tip carry signal.

Tricky these expression pedal setups~! 

Now - it can't get it to go slow enough ? the lowest resistance I can get is 10k and it's still whippin' fast.
RG ? any ideas on how to make it go slower ?

Hmmm.

Just to be sure I understand, you mean the lowest resistance of the LDR is 10K?

If so, then that may be a problem. LDRs have a highish  minimum resistance. Some of them won't go very low. Your LDR may indeed have a 10K minimum for the amount of light your LED can give it. Test this out with an ohmmeter and varying the current through your LED.

Another possibility is that the setup inside the pedal really does want a three-terminal pot and reads the ratio of 5V. In that case, you can add a resistor, maybe 100K or 330K into the expression jack, with the resistor from +5 to the "wiper" terminal, and the LDR from the wiper to ground. That way, the wide range of the LDR can make the output voltage change more. It's worth a try.

[danielzink]

Okay - got it sorted - that it will control the speed on the 'Vibe. Seems the sheild and tip carry signal.

Tricky these expression pedal setups~! 

Now - it can't get it to go slow enough ? the lowest resistance I can get is 10k and it's still whippin' fast.
RG ? any ideas on how to make it go slower ?

Hmmm.

Just to be sure I understand, you mean the lowest resistance of the LDR is 10K?

If so, then that may be a problem. LDRs have a highish  minimum resistance. Some of them won't go very low. Your LDR may indeed have a 10K minimum for the amount of light your LED can give it. Test this out with an ohmmeter and varying the current through your LED.

Another possibility is that the setup inside the pedal really does want a three-terminal pot and reads the ratio of 5V. In that case, you can add a resistor, maybe 100K or 330K into the expression jack, with the resistor from +5 to the "wiper" terminal, and the LDR from the wiper to ground. That way, the wide range of the LDR can make the output voltage change more. It's worth a try.

Apologies R.G.

I meant to say "the lowest reading I can get out of the jack is 10k"

Dan

[R.G.]

I still think I'd try the resistor method to fake a potentiometer with the LDR. A lot depends on what the insides of the pedal do with what the LERA provides it.