Tube boost + overdrive running off a 9 volt battery

[Jdansti]

You can't run a 12V regulator using a 9V supply. Steve's option allows you to power the heaters in parallel with 6V instead of series using 12V. Here's a drawing that should explain it.



Edit:  I'm not 100% sure about this, but the reason Steve probably didn't recommend using a 12V regulator on the 18V output of your charge pump is the pump can't provide the current you need for the heaters.

[jmwreck]

You can't run a 12V regulator using a 9V supply.

yup, I know this, oh so what if I'll change the 15v output from my charge pump to 12v, and from there, I will power the entire circuit with 12v instead of 18v? is it possible? I was thinking of doing the valvemaster instead of the dual caster. I realized that it's a little complicated for my 1st tube project.

Edit:  I'm not 100% sure about this, but the reason Steve probably didn't recommend using a 12V regulator on the 18V output of your charge pump is the pump can't provide the current you need for the heaters.

how about the mica separator?

thanks

[Jdansti]

>yup, I know this, oh so what if I'll change the 15v output from my charge pump to 12v, and from there, I will power the entire circuit with 12v instead of 18v? is it possible? I was thinking of doing the valvemaster instead of the dual caster. I realized that it's a little complicated for my 1st tube project.

It depends on the max current out if your charge pump and the current draw of your heaters. Look at the data sheets to see what they are, and if the total current draw for the heaters and the test of the circuit is less than the max current of your charge pump, you're fine. If not, it's back to the drawing board.

If the charge pump can't handle the heaters, you might want to look around (thrift stores, your friends, maybe stashed somewhere in your house) for a wall wart or laptop power supply that puts out between 12V and 35V AC or DC. From there, it's easy to get the voltages you want.

[jmwreck]

I have a 12v 500ma dc adaptor I used once on my cmoy headphone amp

[Jdansti]

^Ok. You're getting closer. You need two bits of information now.

1) Do you know if your 12VDC PS is regulated?  If you don't know, plug it in and check the voltage out. If it hangs around 12V, you're probably OK. If it's >13V it's probably unregulated and could potentially put more than 12.6V on the heaters.

2) Lets add up the currents of your circuit and see if we're under 500mA. I don't mind doing the work, but I want to help you learn how to do this. I'll start you off with a list and let you research the data sheets for answers. Let us know if you hit a road block.

Find these currents

- tube heater @ 12.6V series X number of tubes = ___mA

-Cathode Current (not "peak") X #of cathodes (2 for one tube and 4 for two tubes)= _____mA

- charge pump input current (if running off of this PS) = _____mA

Add the above currents and you should have a good idea of the current draw of the system.  You might want to add in a 10% factor to cover the rest of the circuit not accounted for above.  If it all adds up to less than 500mA, your good to go, although I would try to leave some room for error. The PS may not have an automatic reset. If you exceed it's capacity you could blow an internal fuse. (I blew one that had an internal fuse recently-it's DOA ).

[iccaros]

the max *** the Madbeans charge pump can supply is 20ma.. so it can not run your heaters, even at 12v.

A 6 volt regulator is only 4 parts, 1 regulator, 3 diodes. and would allow you to use your current power supply and the charge pump for the plates

[jmwreck]

1) Do you know if your 12VDC PS is regulated?  If you don't know, plug it in and check the voltage out. If it hangs around 12V, you're probably OK. If it's >13V it's probably unregulated and could potentially put more than 12.6V on the heaters.

looking at the power supply shell, there's an "IC Regulated" label near the 12Vdc 500ma. I might check it with a meter later.

2) Lets add up the currents of your circuit and see if we're under 500mA. I don't mind doing the work, but I want to help you learn how to do this. I'll start you off with a list and let you research the data sheets for answers. Let us know if you hit a road block.

Find these currents

- tube heater @ 12.6V series X number of tubes = ___mA

12.6 X 1 = 12.6 (since I might do the valvemaster instead of the twin)

-Cathode Current (not "peak") X #of cathodes (2 for one tube and 4 for two tubes)= _____mA

20ma x 2 cathodes(1 tube) = 40

- charge pump input current (if running off of this PS) = _____mA

the max *** the Madbeans charge pump can supply is 20ma.. so it can not run your heaters, even at 12v.

and reading madbean's documentation, it is 20ma, so:

20ma

= total will be 12.6 + 40 + 20 = 72.6 + 10% = ±80ma

am I correct?

A 6 volt regulator is only 4 parts, 1 regulator, 3 diodes. and would allow you to use your current power supply and the charge pump for the plates

what exactly are the diodes?

and is it going to look like this on the entire scheme?



thanks guys

[Jdansti]

>am I correct?

You've listed the voltage and not the current for the tube heaters. Look at this data sheet and you'll see that when you apply 12.6V across the two heaters in series, the current draw is 0.15A (150 mA).
http://www.wooaudio.com/docs/tube_data/12AU7.pdf

If you use one tube, your heater current would be 150mA.
Your cathode current is correct at 40mA
Your charge pump is listed as 20mA
The total for these is 210mA.
Add 10% and your estimate is 231mA, less than 1/2 your PS rating. You should be good with one tube.

If you were to add a second tube, you'd double the heater and cathode currents:
Heaters=300mA
Cathodes=80mA
Charge Pump=20mA
Other: 40mA (estimated)
Total: 440mA

You'd still be under 500mA, but its starting to get close. If our estimate of the "other" current draw is too low, you might exceed the PS current rating.


As for your question about Steve's recommendation, I'm guessing that you'd use 1N400X. We've already determined that you're under 500mA, so you could use anything from 1N4001 to 1N4007.

Edit:

I just looked at your latest schematic and you have a problem with the power. You have the charge pump providing the voltage to the regulator. The regulator's current requirement far exceeds the charge pump's output current. You need to separate regulator and heaters from the rest of the circuit like this:

[jmwreck]

I just looked at your latest schematic and you have a problem with the power. You have the charge pump providing the voltage to the regulator. The regulator's current requirement far exceeds the charge pump's output current. You need to separate regulator and heaters from the rest of the circuit like this:

1. all of this (your revisions on my schematic) will be useless (no more regulator) if I'm going to use my 12v dc 500ma and supply both main circuit and heaters with 12v, right?

2. I understood your revisions and now looking at it, the madbean charge pump has enough current (20ma) to supply the main circuit without the heaters connected to it? if so, then I'll follow your layout.

[iccaros]

sorry I should have been more clear, almost any diode will work, but the 1N4001 drop .7 volts (2 = 1.4v) . For the two in series to ground we are looking for the 1.3 volts to raise the ground reference so the regulator thinks its putting out 5 volts but its putting out 6.3, so a good voltage ranges between 5.67v and 6.93 (6.3v +/- 10%) if I did my math right...

Also I do not believe that tube at low voltage will pass more than 3ma over its cathode, at low voltage it acts a lot like a 12u7 http://www.nj7p.info/Common/Tube/SQL/Tube_query.php?Type=12U7

[iccaros]

2. I understood your revisions and now looking at it, the madbean charge pump has enough current (20ma) to supply the main circuit without the heaters connected to it? if so, then I'll follow your layout.

yes 20ma is plenty to run this with out heaters, it will even work for your two tube design before, it was the heaters that were killing you.

[Jdansti]

>1. all of this (your revisions on my schematic) will be useless (no more regulator) if I'm going to use my 12v dc 500ma and supply both main circuit and heaters with 12v, right?


It depends on whether you want to use the charge pump to get more headroom.

Here's with the charge pump:


Here's without the charge pump:

[jmwreck]

thanks. now Ive seen my 12vdc adaptor is center +, im gonna switch the wire.

[iccaros]

I wire almost everything center positive as it matches other electronics use. Only effects I expect to run off my 1-spot do I wire negative tip.

[Jdansti]

I have a masking tape "flag" near the plugs on all of my power supplies labeled with the voltage, AC or DC, and the plug polarity. I also label the jacks on the pedals too.

[iccaros]

I have a masking tape "flag" near the plugs on all of my power supplies labeled with the voltage, AC or DC, and the plug polarity. I also label the jacks on the pedals too.

I use these --> http://www.amazon.com/Ziotek-Ties-With-Labeling-Plate/dp/B000BSHLJO for that purpose, works well and durable. I am starting to use them in amp builds to label B+ and  2_EQ. This way I can trace the layout better.

[Jdansti]

Great idea, and much cleaner than tape. I think I've seen those at Home Depot-I'll have to check next time I'm there.

[valve999]

change your coupling cap, use  smaller number, if your using .1 use a .01 or .022 ect.. you will roll off some more bass.

Thanks for answer, Iccaros - can I check what you mean by coupling cap - is that the last one before the output i.e. it couples to the next stage? I've built my pedal according to the Valvemaster circuit on p131 - so C3 = 1uf.
Many thanks!

[Henry89789]

I'd suggest a 12AX7 double valvecaster with the valvemaster circuit. You'd need 12V for the heaters and at least 18V for everything else... I found that 12AX7s are more or less useless with anything less than 12V, however with 18V or more they sound great. With this design you'd be able to get some nice crunchy crunch from the first stage and (at least from my experience) HEAVENLY drive with the second stage kicked in. ... Hope it helps.

Toplak666:

I searched this thread for the schematic for the "double valvecaster with the valvemaster circuit"   that you suggested. Is this the schematic (below) for that circuit? The schematic says 12AU7 and you suggested the 12AX7 double valvecaster w/ valvemaster circuit. Is it the same circuit with 12AX7 tubes instead of 12 AU7 tubes? Or is there a  different schematic for the 12AX7 circuit?   Thanks.

[iccaros]

change your coupling cap, use  smaller number, if your using .1 use a .01 or .022 ect.. you will roll off some more bass.

Thanks for answer, Iccaros - can I check what you mean by coupling cap - is that the last one before the output i.e. it couples to the next stage? I've built my pedal according to the Valvemaster circuit on p131 - so C3 = 1uf.
Many thanks!

There are several locations, you can change c3 but you may find a better sound by changing c2 to a .0022, or by changing the cathode bypass capasitors (the 10uf) to a 1 or .1. if you roll off bass early your not boosting frequencies in latter stages.