BAJA Real Tube Drive pedal project

bajaman · Post by **bajaman** » 08 Apr 2015, 10:04

glad you like it

mifl · Post by **mifl** » 21 Jul 2015, 20:54

bajaman wrote: members/bajaman/Baja/Baja%20Real%20Tube ... ematic.png

Hi mister !!!!!!

I'm building it
And wondering,you don't draw the two 1n4148 in this schematic ?

jesven · Post by **jesven** » 12 Oct 2015, 16:31

Hello everyone, first of all , need to thank bajaman fo this pedal, you're a legend in Mexico... at least in the diy pedals community.

Well , recently have interest on tube pedals even when I've never had one and never tried one before , but I can say they sound great in the samples so I decided to build my own baja tube driver not only the 12ax7 version but also the 6N17b (I ordered some pieces from Moscow ) I've been working on the 12ax7 version and I've finished building it but I can't give it a try cuz I don't have any 16v Ac PS. So I have a question , maybe you've heard off before, how can I build the power supply for this pedal.? Hope you can help me.
Thanks

finkployd · Post by **finkployd** » 12 Oct 2015, 17:58

I've used this one

DrNomis · Post by **DrNomis** » 12 Oct 2015, 19:24

If you're going to buy a commercially-made AC adaptor for the Baja Real Tube Overdrive just make sure it really is one that puts out AC rather than DC, otherwise the pedal won't work properly, I've seen some adaptors described as AC types when they're really DC types....

jesven · Post by **jesven** » 13 Oct 2015, 11:37

But if i want ro do de power supply ... How can i do it.?

bajaman · Post by **bajaman** » 13 Oct 2015, 20:29

buy a 16v AC @ at least 500mA transformer

jesven · Post by **jesven** » 16 Oct 2015, 23:20

I couldn't find anything, only a 20v A.C. 1200mA, can I use this one .?

bajaman · Post by **bajaman** » 16 Oct 2015, 23:56

I couldn't find anything, only a 20v A.C. 1200mA, can I use this one .?

If you do you will have to ensure that the input electrolytic capacitors are rated at at least 35V dc, and you will have to increase the 330 ohm 5 watt resistor to 500 ohms AND it will get VERY HOT!
As an alternative you could substitute this for a 7812 regulator mounted on a small heatsink. Easier to obtain the correct voltage power supply though - check ebay or ali express etc

jesven · Post by **jesven** » 17 Oct 2015, 03:00

Well i bought a 15-16v AC but when i messure the voltage , it says 20.6 v , don't know if the unit is not working or something,I asked some guys at the Mexican community and they say it's OK cuz its not regulated but I want to ensure the pedal won't get fried. Thanks!

bajaman · Post by **bajaman** » 17 Oct 2015, 05:07

not regulated - aaaaaaaaaaaaaaaaaaaaaaaagh you have probably been sold a DC not AC adaptor

jesven · Post by **jesven** » 17 Oct 2015, 05:16

Don't know the box says "input: 120vAC 60Hz output: 15-16v AC. Is it the wrong one .?

bajaman · Post by **bajaman** » 17 Oct 2015, 07:35

If that is what it says on the box it should work ok

mifl · Post by **mifl** » 17 Oct 2015, 07:43

jesven wrote:Don't know the box says "input: 120vAC 60Hz output: 15-16v AC. Is it the wrong one .?

Hi !!!

It's ok

Voltage measurment is higher than written,it's normal on AC (Vac x1.4)

DrNomis · Post by **DrNomis** » 17 Oct 2015, 13:30

jesven wrote:Don't know the box says "input: 120vAC 60Hz output: 15-16v AC. Is it the wrong one .?

If it's a genuine AC to AC (not AC to DC) plugpack it should work fine, the voltage will read a bit higher on a multimeter set to read AC Volts, when a Multimeter is measuring AC Volts it is measuring it as Volts RMS (Root Mean Squared)...

The reason why you need to use an AC to AC plugpack to power the Baja Real Tube Overdrive is because in the power supply section of the BRTO circuit, there are two power-diodes, one supplies rectified current to the positive supply (LM7815 and associated filter caps) and the other power-diode supplies rectified current to the negative supply (LM7915 and associated filter caps), if you try to power the BRTO circuit with an AC to DC plugpack one of the power supplies will not work since one of the power-diodes will be reverse-biased and will not conduct current, if an AC to AC plugpack is used then both of the power supplies will work properly since each power diode will conduct on alternate halves of the AC supply....

jesven · Post by **jesven** » 18 Oct 2015, 04:14

So it's OK or should I go to get my refund .? I mean 4 more v is not excessive .? I'm still afraid of frying something

DrNomis · Post by **DrNomis** » 18 Oct 2015, 14:19

jesven wrote:So it's OK or should I go to get my refund .? I mean 4 more v is not excessive .? I'm still afraid of frying something

Provided that the four 470uF caps in the power supply are rated for 35V DC, you should not have any problems, you might need to change the value of the current limiting resistor for the valve's heater supply to get about 12.6V going to it, in my BRTO build I used a 16V AC/1.25A plugpack and found that I needed a 33 Ohm/5 Watt resistor for the heater supply current limiting resistor....

If you don't use four 470uF/35V caps in the power supply lower voltage ones may explode....

jesven · Post by **jesven** » 19 Oct 2015, 23:50

Well , I haven't try the pedal yet , I'm still waiting for the sockets to arrive (those are really hard to find in Mexico so I ordered some from Russia) but I went where I bought the power supply the only thing I could find was a 15v ac , this time it seems to work OK, the guy in the store told me that should be no problem cuz the difference is just 1v , hope this one works fine. What do you think .?

DrNomis · Post by **DrNomis** » 20 Oct 2015, 02:42

jesven wrote:Well , I haven't try the pedal yet , I'm still waiting for the sockets to arrive (those are really hard to find in Mexico so I ordered some from Russia) but I went where I bought the power supply the only thing I could find was a 15v ac , this time it seems to work OK, the guy in the store told me that should be no problem cuz the difference is just 1v , hope this one works fine. What do you think .?

A 15V AC plugpack should work well enough provided the current output is at least 500mA, you might need to tweak the value of the heater supply current-limiting resistor to get about 12.6V AC across pins 4 and 5 of the 12AX7 valve, assuming the heater supply current-limiting resistor is 10 Ohms, if the heater supply voltage on pins 4 and 5 is lower than 12.6V AC try the next lower value of resistance (eg: 8k2), if the heater supply voltage is greater than 12.6V AC try the next higher value of resistance (eg: 12 Ohms)....

Use a multimeter set to AC voltage to measure the voltage on pins 4 and 5 of the 12AX7 valve.....

jesven · Post by **jesven** » 20 Oct 2015, 03:08

Thank you Dr. Nomis , hope I can give it a try soon.
Also I'm working on the 6N17B version so I hope I succeed.

BAJA Real Tube Drive pedal project [documentation]