Easy Vibe Questions

[Kevin Mitchell]

Hello, I'm new to this forum and this hobby as well. I've recently gotten the hang of creating a perfect pcb but I'm not so familiar with many parts. Observing the available pictures of an Easy Vibe circuit I have noticed variations in the trim pots used. I'm talking about the 1k trimmer used in John Hollis's Easy Vibe and similar projects. I have these on hand and I am hoping it does what I need it to do without any problem. My doubt is only due to my unfamiliarity of parts.

I am using this 1k trimmer;


Before I connect all the wires I was hoping someone could confirm that this trim pot will work for this project.

I am aware that being so new into this hobby I have started with a difficult circuit. The past few weeks have been allot of trial and error and I'm confident with what I've learnt so far this pedal is close to being complete (and working). Can't wait to have it on my board so I can enjoy it and move on to other projects.

Any insight is very much appreciated and I thank you for the assistance.  

[GibsonGM]

Well, it calls for a 1K trimmer, and that is one, so you should be all set!  I think I may have used a 2k, or 5k, which just makes it a little harder to dial in (the range where the 1K is available gets smaller).   
Good luck, ask if you get stuck!!

[Kevin Mitchell]

That's what I suspected thank you very much! I'm about to connect all the external components and give it a whirl. I was very careful with this one so hopefully there wont be much to troubleshoot!

[GibsonGM]

Hope it goes together easily for you. Took me a while before I attempted the EV (on perf!!), but didn't take too much debugging. It's so big, you tend to be very careful with assembly!   Let us know how it works!

[Kevin Mitchell]

Well, the c9 (1st cap to get power) keeps blowing... I'm using a 470uf 16v and sound does goes through. Although none of the leds are lighting up. Any ideas?

Also I have a few other questions;
If I'm not using a millennium bypass as suggested in the layout would the dpdt switch need to be wired differently?
Using an ac adapter instead of a battery snap I want to use a mono jack instead of a stereo, where should the ground from the adapter connect to?

The layout I'm talking about is available on John Hollis's site.

[duck_arse]

that ac adaptor you mention. what does its ratings plate say, ac or dc? if you feed your circuit ac, it will blow more than the first cap.

[Kevin Mitchell]

The description of the order reads "DC-022 2.1 x 5.5 mm" which I'm confident is the corrects specs for this project. Just a basic plastic DC power adapter.

EDIT; Also it blew a cap with just a 9v battery attached. (Had to make sure it wasn't my pedal power) So I'm sure the power supply isn't the issue.

Sorry, should have written DC power adapter not AC in my previous post.

[Kevin Mitchell]

Do you think wiring the LEDs backwards could have done this? That's my only thought. But I'm also very inexperienced.

How can I tell?

[GibsonGM]

Do you have a DMM? (digital multi meter).    If you do, you probably have a setting that will tell you the Vf (forward voltage) of the diode....it will not work if you have the leads wrong way around.     I don't think backwards LEDs would cause that, but do make sure they're in right!    If you put in AC power, or too high a voltage, you will pop the cap...maybe the CAP was in backwards?

Good to get the power section going first, THEN hook it up to the opamps and Vref stuff.

An easier way to spot which way around the LED is....the "long leg" of the LED is generally the positive (anode).   The flat spot on the body of the LED is typically the negative (cathode, the 'band' on a schematic).   

The 'big thing' for me was getting the power supply right, as you have the positive for the opamps, the VRef (REFERENCE VOLTAGE), and ground.    I was new enough when I made mine that I didn't pay attention and in places treated the "+" and Vref as the same thing!   So be careful.

I try to build stuff like this and test it, THEN put the stomp switch in so I know it works and if it later doesn't, I'm pretty sure it's the switch wiring....just tricks you learn after a long time doing this     

I suggest using the battery for testing til you get it going, and to check the wall wart supply with a meter to see what you get...could EASILY be too high of a voltage as you're not dragging it down with its rated current, most likely...

[Kevin Mitchell]

Wow thanks for the info! I do have a DMM but it isn't all that great.

So semi-good news. After replacing the cap and switching the leds around there was one pulsating light and some light-dirty sound with my guitar. Still no glow from the bias though. After tampering with the trim pot the led stays solid which isn't good. I'm going to check for bad solder joints and resolder the trim pot. Also the cap seems to be holding up this time.

[Kevin Mitchell]

So now that single light is pulsating but no sound is coming through the board. Trying to figure this out before I decide to replace the other op-amps. I'm using TL062s.

Debugging is a pain lol. But I am very excited! I really should utilize my multimeter about now.

[GibsonGM]

Did you use the recommended size LEDs?    The 2 LEDs on the bias should be on/pulsate with the oscillator when power is applied.

What I'd do is get some voltages and fill the debugging page out (copy/paste to here)   http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

Ya, debugging is a pain, but it makes the final product more rewarding, lol!!!    First I'd measure the voltage in (battery/wall wart), and then take a reading of voltage at the TL062 power pins, and the Vref voltage (especially Vref).    That can tell you a lot!   If the LEDs aren't in right, that will be way off (perhaps leading to a fuzzy sound.....).  If you see your battery draining fast, like 8.4v to 8.0v to 7.8 v in 1 minute, then you have a short...

The place I made a huge error was at the four 1N914's...had them connected to GROUND rather than Vref.  Those also have to be oriented correctly, BTW.... You probably should check that ALL the Vref connections are right!     If you can, post a link to the schematic you've worked from, too, ok?  I only have the hand-drawn original by Hollis, which is what I'm going by.   Easy to mistake Vref for ground....with power on, each point there should be the same as vref and NOT 0 volts...


After you fill out the debugging, we'll talk about audio probes, which you'll want to make.    http://www.diystompboxes.com/pedals/debug.html

[Kevin Mitchell]

I really appreciate the tips! And yes I am using 3mm red leds.

I'm using the available pcb layout on his site which is only available in pdf. Google easy vibe and check out the 3rd link from the top.

[GibsonGM]

Post a link to the schematic you're using...it's more polite    

[deadastronaut]

funny ive just redrawn this and plan to breadboard it soon, ...(john hollis schemo)

@kevin..

on that pdf, where you see C9 / C10 on that board...the positive sides of the caps go to the 'square' pads ok..

same with led5/6 too...'square pads' are positive.


the four leds to ldrs: 

from r18 (220r) goes to + (long leg of led)  of led 4...

and 3 /2/1 are orientated the same way as 4 is by the look of the pcb layout..


+ - + - + - + -

double check your diodes are the right way round too..

rob.

                   

[Kevin Mitchell]

This is John's hand drawn schematic:
http://www.hollis.co.uk/john/easyvibe.jpg

Yes the Electrolytic caps, bias leds and diodes are all in right. I even transferred a layout to the underside to ensure my components would be put in correctly. Just the 4 main leds were backwards because they don't have a square pad like the others to indicate negative which is an honest mistake if you're not familiar with assembling a pcb (which I'm still learning).

Soon I'll create my own layout with mods to make assembling allot easier but for now I have to figure this darn thing out so I can get to that point...

A couple days ago I mentioned how I got some sound out of it and one led was working correctly. But now once again it stays solid, nothing else lights up and I don't get sound through the board. So I don't think it has to do with the orientation of a component but perhaps some bad parts. I just don't understand how to find them.

[Kevin Mitchell]

on that pdf, where you see C9 / C10 on that board...the positive sides of the caps go to the 'square' pads ok..

You know, that would make allot more sense... Not sure why it semi-worked for briefly though if I have 6 components in backwards lol. Fingers crossed.

[deadastronaut]

kevin, i'm about too breadboard this now...so i can tinker with it..

[petemoore]

 I always compare or use a battery, that way if a PS does as good a job I know the DC is really 'good' DC.
The LFO and signal paths are 'separate' circuits, the LFO oscillator just varies the flow through the LED's, so that'll work [or not] regardless of the signal processing circuits [phase stages].
Debugging the signal circuit to find the problem before messing with a hot iron is suggested.
Taking voltage measurements and applying the audio probe should better isolate where to apply soldering or de-soldering efforts.

[GibsonGM]

Well, Kevin - I think you're going to have to post the voltages on each of your IC pins!   Clip your black meter probe to the battery "-", or wherever you can find a known ground (where it enters the board, etc).   Then probe each pin CAREFULLY with the red "+" probe.   Careful not to short any pins together, and make sure your meter is set to "DC volts".    Make a nice 'chart' of your voltages and post, ok?

See this: http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

There are a few tricks that can be done with a meter and whatnot, but first let's see what is actually happening at the pins...