freestompboxes.org

does anybody have the baja schematic for active pickups??, id would like to try it but i have seen many different sch everywhere, so im looking for it in here, if BAJA can tell me will be amazing, looking for the EMG81, also if anybody have the LM4250 on smd eagle library its welcome too

Hi I want try out the Baja active pickup system did anyone are use it ? İts good ? So can anyone post schematic please ?( not trace file) thanks

google is your friend
https://www.electrosmash.com/emg81#link5
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cheers
bajaman

Moderator: modified the link to go directly to the Bajaman's schematic and added the schematic to this post. Make sure you check the article, though, it's a treasure trove of information regarding both Bajaman's schematic and active pickups.

bajaman wrote:google is your friend
https://www.electrosmash.com/emg81
scroll down
cheers
bajaman

I know the site but cant see schematic before my bad sorry I cant find the MMDB701 Diode. Have any replace for it

Rauch

This diode does nothing to the signal, it is only reverse power flow protection so you can use anyone.

EddieTavares wrote:Rauch

This diode does nothing to the signal, it is only reverse power flow protection so you can use anyone.

Ex. 1N4148 ? Thanks

Yes, it'll work perfectly!

An option something better is to use an schottky diode, anyone. There is a little voltage drop (aprox. 0,6v) when 1N4148 is used in this way, it does not affect your tone when the battery is fully charged.

Another good Idea is to use it in parallel as it is used in pedals.

EddieTavares wrote:Yes, it'll work perfectly!

An option something better is to use an schottky diode, anyone. There is a little voltage drop (aprox. 0,6v) when 1N4148 is used in this way, it does not affect your tone when the battery is fully charged.

Another good Idea is to use it in parallel as it is used in pedals.

I found mmbd diode footprint and add it bit I cant understand one thing 4205 pin 4 ground and pin 7 to 9v+ is it ? Or something else ?

I wonder if its suitable to use a 071 or 741 instead of 4250, as its an unobtanium already..

slammer88 wrote: ↑19 Mar 2024, 09:12 I wonder if its suitable to use a 071 or 741 instead of 4250, as its an unobtanium already..

Either one of these should work OK, just omit the programming resistor R8 and leave the op amp pin 8 floating.

And what about a 2 wire pickup? Mine only has white and black ones, white being the live one and the other, black being the ground. Is it usable in this scenario?

mauman wrote: ↑19 Mar 2024, 13:17

slammer88 wrote: ↑19 Mar 2024, 09:12 I wonder if its suitable to use a 071 or 741 instead of 4250, as its an unobtanium already..

Either one of these should work OK, just omit the programming resistor R8 and leave the op amp pin 8 floating.

I just ran across another substitute for the 4250, though it's also obsolete. If you can locate one, the Motorola MC3476 P1 specs are very close to the 4250, and it also accommodates the programming resistor R8 on pin 8. The datasheet has info on choosing this resistor, but the bajaman's value of 1M for the 4250 will give you similar results with the 3476. BTW, this IC was used in the op-amp version of the Barcus Berry 1330 piezo preamp, but with a lower programming resistor value of 220k resulting in a higher quiescent current.

Regarding using this circuit for a two-wire humbucker, it's designed as a differential amp, which requires two complementary inputs, in this case the two coils of the same humbucker. Providing two inputs from two different two-wire humbuckers is not the same. I'd look for a different preamp for your two-wire pickup, there are some here on the forum including viewtopic.php?t=27819 and viewtopic.php?t=431