EMG Active Pickup Circuit?

[CHEEZOR]

The battery -ve ONLY to the "ring" connection, all other ground connections to the "sleeve".

This is so that when you insert a mono jack it shorts the ring to sleeve connections and connects the battery to the preamps.

Well then, as i've said, if i connect the -ive lug to "ring" and use "yellow" cable as out, i can't get any sound from guitar, but if i use use red-white cables, i get a sound but its significantly weaker that it was on yellow..

Just to be clear, what me and deltafred are talking about is this:

wiring.PNG (57.92 KiB) Viewed 2620 times

[slammer88]

The battery -ve ONLY to the "ring" connection, all other ground connections to the "sleeve".

This is so that when you insert a mono jack it shorts the ring to sleeve connections and connects the battery to the preamps.

Well then, as i've said, if i connect the -ive lug to "ring" and use "yellow" cable as out, i can't get any sound from guitar, but if i use use red-white cables, i get a sound but its significantly weaker that it was on yellow..

Just to be clear, what me and deltafred are talking about is this:

wiring.PNG

i know that, thanks

[CHEEZOR]

i know that, thanks

Sorry if I was over-explaining that, , but neither me or deltafred said anything about moving the yellow wire. Maybe I'm not understanding something.

I was assuming that you were disconnecting the yellow wire and reconnecting it either to the OUT from the preamp circuit or to the jack's tip (Neither of which make any sense to me). You also mentioned that you tried using the Red/White wires instead of the Yellow, but you got a weaker signal than using the only the Yellow (which you said had NO signal, so I don't see how it could get weaker than no signal). So thats why I posted the image because I was totally confused.

You shouldn't connect the Red/White wires to anything. Only to each other like they are in the image. In fact, everything should be like it is in the image. If you have it hooked up like the image, then maybe the wiring isn't the problem. I would check the pickup, preamp, jack, and instrument cable to make sure all of those work. Hope this helps.

Note: after looking at your image again, I would consider wiring the volume pot as shown in this updated version of your image.

wiring.PNG (59.27 KiB) Viewed 2616 times

[slammer88]

i know that, thanks

Sorry if I was over-explaining that, , but neither me or deltafred said anything about moving the yellow wire. Maybe I'm not understanding something.

I was assuming that you were disconnecting the yellow wire and reconnecting it either to the OUT from the preamp circuit or to the jack's tip (Neither of which make any sense to me). You also mentioned that you tried using the Red/White wires instead of the Yellow, but you got a weaker signal than using the only the Yellow (which you said had NO signal, so I don't see how it could get weaker than no signal). So thats why I posted the image because I was totally confused.

You shouldn't connect the Red/White wires to anything. Only to each other like they are in the image. In fact, everything should be like it is in the image. If you have it hooked up like the image, then maybe the wiring isn't the problem. I would check the pickup, preamp, jack, and instrument cable to make sure all of those work. Hope this helps.

Note: after looking at your image again, I would consider wiring the volume pot as shown in this updated version of your image.

wiring.PNG

I'm trying this wiring right now, i'll report some time later

P.S: WORKED LIKE A CHARM! Thank you!

[CHEEZOR]

P.S: WORKED LIKE A CHARM! Thank you!

Glad to hear it!

[skylark44]

It looked like there was no input (coming from the preamp) connecting to the input lug of the volume pot (in the first diagram)...therefore...no signal coming from it. The pickup's red & white wires are most likely it's series connection (between coils)...that's probably why the pickup's signal decreased, when they were disconnected .

[slammer88]

It looked like there was no input (coming from the preamp) connecting to the input lug of the volume pot (in the first diagram)...therefore...no signal coming from it. The pickup's red & white wires are most likely it's series connection (between coils)...that's probably why the pickup's signal decreased, when they were disconnected .

most probably..one thing is, i've never used the pot's 3rd lug before, so i didnt even think that might work

[gnognofasciani]

I finally built it and the sound is great, but i have one problem:
- my color code is green for HOT, red and white together, black and bare to GND for standard wiring and green+black HOT and red and white to GND for parallel wiring;
- I wired green and black as +IN and -IN and red+white to GND;
- at first I used the same wiring for both the humbuckers but i got out-of-phase sound when both selected;
- then i tried inverting the wiring for one of the pickups: I used the red and white (previously to ground) as +IN and -IN and the green and black to GND but nothing changed...

Should I try inverting green and black (or red and white)? Does anybody have a clue?

Thanks!

[gnognofasciani]

Ok, maybe i got it: looking at the schematic (https://www.freestompboxes.org/download/ ... &mode=view) i noticed that when both pickups are selected the 2 10k resistor at the output create a divider...i will try to remove them as soon as i can!

[gnognofasciani]

Unfortunately that was not the reason...I really like the sound of the center position the way it is right now, at least with distortion...I just would like to know what's wrong

[EddieTavares]

You can use a single 10k resistor after the switch

[ansil]

In the case of the duncan you dont cut anything. Normal pickup wiring. Ground the coil cut side. Lift the previous ground. Green and black still go to the opamp inputs

[ansil]

ok no edit button. but apparently enough i found out something quite interesting. all the former sites i went on wiring and even the book i first learned out of. did not describe parallel wiring like this. lol so now i am unsure what the hell wiring i have been doing on this one. out of phase humbucking. anyway my flub

[EddieTavares]

If you intend to activate a seymour duncan, consider this picture, the wiring shcematic is what you have to do.

[EddieTavares]

askwho69

To understand what it means, you have to know how opamps works. Yes this is not paralell and this is not series.

[blackbunny]

This is a balanced input circuit, which is different from the EMG circuit because it "floats" the ends of the series wired coils and feeds them into a differential amplifier.
This is how balanced microphone preamps work and is rarely used in guitar circuits.
The Duncan balanced input preamps would make a great topic, separate from EMG.

[EddieTavares]

http://www.ti.com/lit/ds/symlink/tlc251.pdf i tried this Opamp it works cool EddieTavares can you check this opamp? TLC251... my only problem is to calculate the bias for lower consumption . . . i dont know the math.

You can try 100k to 4M even 10M, anyone will work, but I found very good results with 100k resistor working with TL061. Usually I play guitar about 10 ours a week and sometimes I forgot my guitar conected... so, one batery 9v has working fine more than 8 months with no tone loss.

There is no secrets about bias resistor folow your heart, ops... folow your ears.

[deltafred]

You can try 100k to 4M even 10M, anyone will work, but I found very good results with 100k resistor working with TL061.

The bias resistor is for programable opamps only (like the LM4250, TLC251) not TL061.

Pin 8 of the TL061 is marked as NC (no connection) and as such should be left open circuit.

[deltafred]

That's why i ask i was confuse about 100k working in TL061 . . .

Never believe everything (some say anything) you read on the internet unless you first know it to be true.

By the way how can i program the TLC251..? i've been using this opamp and sounds cool to me...

Any suggestions?

Short answer.
Read digest and understand the datasheet then design your own circuit.

Long answer.
Taken from the datasheet

using BIAS SELECT
The TLC251 has a terminal called BIAS SELECT that allows the selection of one of three IDD conditions (10,
150, and 1000 μA typical). This allows the user to trade-off power and ac performance. As shown in the typical
supply current (IDD) versus supply voltage (VDD) curves (Figure 4), the IDD varies only slightly from 4 V to 16 V.
Below 4 V, the IDD varies more significantly. Note that the IDD values in the medium- and low-bias modes at
VDD = 1.4 V are typically 2 μA, and in the high mode are typically 12 μA. The following table shows the
recommended BIAS SELECT connections at VDD = 10 V

What this is saying is that there are 3 bias modes (low, medium, high) that give 3 different performance characteristics, again low, medium and high. With 3 current consumptions, and you guessed it low, medium and high.

For a 10v supply
Low bias mode - connect pin 8 to +ve supply, this has a low current consumption
Medium bias mode - connect pin 8 to between 0.8 V and 9.2 V medium current consumption.
High bias mode - connect pin 8 to ground Ground, this has the highest current consumption.

This is not the same as the LM4250 that uses a resistor to set a variable bias with variable performance and current consumption. I have used the LM4250 and it is easy to program. I have never used the TLC251 but it looks like you need a voltage (or a pot or 2 resistors) on pin 8 not a single resistor.

There are reasons why the LM4250 is so popular for low power circuits :-
Easy to use.
Low parts count.
Cheap.
Very low current consumption can be achieved.

EMG engineers seemed to think it was best suited for the job. With the TLC251 you are tied to one of 3 preset current consumption figures, the LM4250 current is variable and set with one resistor.

[EddieTavares]

Guys forgive-me.

I understood that askwho69 were arsking about voltage divider bias resistors.