THE ENGINEER'S THUMB... At last, a better compressor!

[bluebunny]

I really like the millenium bypass by the way. Are there anythings it wont work with?

Anything where there isn't a DC route to ground from the output.  As an example, take a look at the Brian May Boost at geofex.com.

[Kipper4]

Ok cool.
That's a shame that was my first from scratch build. I guess i'll just have to do true bypass on this one.
Is it still possible to put a resistor on the input to ground on this type of circuit then?

[deadastronaut]

@Rich it is there already..the 10M.


?..the junction of the emitter, and the 10k..

do both points (that junction) join and  go to pin 1 and 5?...


hold on, on jons layout he has pins 16/9/10.. and 6/7/8  joined..to ground....

[merlinb]

Is there a way of using millenium bypass with an input jack ground switch for use with batterys?

The Engineer's Thumb already does this, so it must be possible 
See?

[merlinb]

Ok cool.
That's a shame that was my first from scratch build. I guess i'll just have to do true bypass on this one.
Is it still possible to put a resistor on the input to ground on this type of circuit then?

You can always use the Millennium bypass- just add a big resistor to ground if there isn't already one there.

[midwayfair]

hold on, on jons layout he has pins 16/9/10.. and 6/7/8  joined..to ground....

I grounded out the unused half of the LM13700.

[Kipper4]

Ok cool.
That's a shame that was my first from scratch build. I guess i'll just have to do true bypass on this one.
Is it still possible to put a resistor on the input to ground on this type of circuit then?

i was talking about the treble booster here Astro. I could have made that more plain, Sorry

Fair points Merlin i missed that. I see it uses the +9v on the switch rather than the ground. When i did it the other way round the effect did nothing . Mind you i did have other issues, so i could have been those too.

I did ground out the unused bits on the lm 13700 as per johns Perf layout.

I struggled to make this fit in a 1590B box. I had to trim the circuit board as tight as i could go.
So i'm now rethinking my planning and circuit board maximum size. I need to rationalise space. How on earth John gets it in a 1590A i dont know. YET.

[smallbearelec]

A guy wrote to me, said that he ordered the surface-mount 13700 from me for this build because that's all I had. I Do stock the NJM13600 in DIP, which Merlin says should work; the Engineer's Thumb does not use the output Darlington stage, and that's the only diff between those chips. If anyone has used the 13600 successfully, pls advise. I have offered to send one to my customer, and will advise hoiw that works out.

Regards
SD

[bluebunny]

Ok cool.
That's a shame that was my first from scratch build. I guess i'll just have to do true bypass on this one.
Is it still possible to put a resistor on the input to ground on this type of circuit then?

You can always use the Millennium bypass- just add a big resistor to ground if there isn't already one there.

Yep, which is is what I ended up doing on mine, once I'd worked out why it wasn't working!     In fact, it was so bl00dy loud (according to my tame guitarist), that the second one I built (for his birthday) had a "convenient" volume pot at the output.

How on earth John gets it in a 1590A i dont know. YET.

Said this before, but I don't know how Jon gets all that handwriting in his 1590A builds!   

[midwayfair]

So i'm now rethinking my planning and circuit board maximum size. I need to rationalise space. How on earth John gets it in a 1590A i dont know. YET.

It involves some 1/8W resistors and an extra jumper to shave off a couple rows from my perfboard layout. Short electrolytics/tantalum/multilayer ceramic caps and all that jazz.

https://dl.dropbox.com/u/9878279/Jon%20Patton%27s%20layouts/Engineer%27s%20Thumb%20-%20Micro.pdf

[garcho]

What I'm most impressed with is how you guys fit this in a 1590A without making your own PCBs. Raw will.

Love this compressor by the way, thanks for sharing Merlin.

[deadastronaut]

i breadboarded this a few times yesterday but couldn't get the bugger going....

might give it another go today...2n3906 is ok for this i have read?..

[merlinb]

might give it another go today...2n3906 is ok for this i have read?..

Yes, any PNP should work.

[merlinb]

I have received a few questions about the ET recently, so I thought I'd post an official 5-knob version, in case there was any confuson about how to set things up:

[KazooMan]

A guy wrote to me, said that he ordered the surface-mount 13700 from me for this build because that's all I had. I Do stock the NJM13600 in DIP, which Merlin says should work; the Engineer's Thumb does not use the output Darlington stage, and that's the only diff between those chips. If anyone has used the 13600 successfully, pls advise. I have offered to send one to my customer, and will advise hoiw that works out.

Regards
SD

That would be me.  

I missed the 13600 when I was going through the parts list  

Added later, some of what I thought I wrote disappeared:  I have actually etched the board and populated it with the components I have.  I installed a socket for the 13600 chip that Steve has generously already sent me in the mail.  I have plans to attach "legs" to the surface mounted chip to get it into the socket.  I think that this will work since there are very few pins being used.  I have checked out wires for the job and found a bunch of resistors that I have which seat perfectly in the Mill-Max socket I am using. 

I should add that in looking at the pcb layout it looks like it could be modified to accept the surface mounted chip.


Note to Steve:  It would be great if you could somehow incorporate a way to search for ICs by the number without the initial letters.  I was looking to find LM13700 and only found the V13700M by scrolling through your entire inventory.  All bets are that there will be no discernible difference, but I will report back.  From looking at the pcb layout it looks like it would be possible to alter it to use the surface mount.

Geez... This was also lost in the original posting.  It would be GREAT if there was a way to search for chips with just the numbers and not the initial letter designations (manufacturers???).  (something like:  **number*).   An even better wish would be for a search that returned acceptable replacements!!!    I know that is too much to ask.  Thanks for supplying the parts that you do.  Small Bear is my Number One resource.

Oh, I should add that I have THREE shipments coming from Steve.  The original, the 13600 he offered to send me, and a few parts to repair a Dunlop Wah that I forgot to add to the original order.  I will be watching the mailbox eagerly!

[deadastronaut]

I have received a few questions about the ET recently, so I thought I'd post an official 5-knob version, in case there was any confuson about how to set things up:

thanks merlin...i'll breadboard this again..

are the leds important on this?..

i noticed that on this sche you have 10uf/1k..to level pot, but on the pdf schem its 1k/10uf....?

[merlinb]

are the leds important on this?..

They're not essential, but I would recommend them to avoid any really ugly distortion.

i noticed that on this schem you have 10uf/1k..to level pot, but on the pdf schem its 1k/10uf....?

They're in series, so it makes no difference either way!

[earthtonesaudio]

Merlin, check the input section of the bypass switch on your latest revision.

[merlinb]

Merlin, check the input section of the bypass switch on your latest revision.

Well spotted, thanks! Fixed now.

[midwayfair]

Just wanted to give everyone a heads-up: Jacob Kokura just released a PCB of the Thumb using the 3080 chip in place of the LM13700:
jmkpcbs.com/JMK_PCBs/Store.html

(I'm not affiliated.)

It's a very nice, clean looking layout; I can't comment on any sound differences between the two chips as I haven't built it that way yet, but Jacob has said that he couldn't hear an appreciable difference.

I thought this might be of interest to the folks that don't etch or do vero/perfboard.