Battery powered Push pull amp

[iccaros]

For discussion, I have a working prototype, it is far from complete..
Using three 6418.. as preamp and paraphase PI.
The first is wired as a pentode, second and third in Triodmode.
Two 5840 in push pull

Using a Max 1044 to boost voltage, from 12v to 61v. The voltage drops to 49V when the tubes start conducting
using a 70v line transformer tap common and .62w for the plates and 2.5w as center tap.
Will post Schematic once I draw one.. I am sure this can be refined for more volume (better voltage multiplier) and more clean head room..


sample here

All suggestions on values welcome..
I do not want to build a SMPS and I want to use BATT to run.. So if anyone has a better voltage Multiplier please let me know..

[imaradiostar]

Have you tried an ebay nixie power supply? I'm about to buy one for a project- very useful if you only need 20-40 ma power from 9 to 15 volts.

I have a prototype on my bench that uses half of a 12v cig lighter inverter- only the boost half, not the half that generates AC from the high voltage. It makes a really solid 280ish volts and is very efficient. Look for cheap inverters at wal mart or target and probe the board to figure out what to keep- usually only the stuff on the 12v side of the boost transformer. Get some high speed rectifiers and you'll be all set. Mine will easily put out 200ma with almost no sag and requires little capacitance since the switching frequency is supersonic. Add a resistor for sag if needed and filter downstream.

jamie

[Steve Conner]

You say you don't want to build a SMPS. But you've already built a poor performing one (and got the schematic wrong) so why not make the effort to build a decent one.

I've had great results using the LM2586, admittedly in scientific instruments and not guitar amps. I use several of them to generate the voltages I need from a DC bus that can vary between 6-12V depending on the battery state, and if the wall wart is plugged in.

As a plain boost converter it can only handle about 60V, but with a suitably wound flyback transformer you can get any output voltage you want. I've seen it used to generate thousands of volts for a CRT. It has a proper PWM control loop that won't generate audible noise, as the MC34063 and many other cheap converters do.

Jamie's plan of using a car inverter is a good one if you're hungry for more power.

[iccaros]

@imaradiostar I have one of those inverters also, but am not sure which is the boots part? In any case one goal is to use batteries, which mine just killed batts in min.. but I will keep playing with it.. I only need 100v for this.. so that maybe overkill will have to look. If you have an example I would love to see it.

I have some issues with a SMPS like a 555 based or max 1771, One is Hetrodyning if I use a plug instead of batt, as finding a non SMPS wall wart that has any amperage is hard. Second I need two taps, one for about 30v as that is the max for the 6418 and about 80 - 100v for the 5840 not to exceed 120v. the max1044 is what I was playing with on the bread board (I updated the Schematic , if its still wrong please let me know where, I can't see it), but its there for proof of concepts.
the LM2586 is interesting.. I wonder do you have an example flyback design high voltage with it, or could I just put a 1:5 transformer and voltage divide r-sence? I am not very good at SMPS so I am looking at simple.

Thanks for the advice..

[imaradiostar]

Perhaps Steve or R.G. could help with a "forum supply" and point to off the shelf toroids/coils that would be appropriate to use with such a supply. I would tend to use what I found in things I took apart and I don't have any knowledge of the math to build one correctly other than what I find on datasheets. That said, most of the circuits Steve is describing have less parts than the switched cap circuit you already built and are capable of a much wider range of voltages and better voltage regulation.

jamie

[soundguruman]

There used to be a 90 volt rectangle battery, about the size of what a 9 volt battery is today, a bit longer...
It was used for powering peanut tubes, in portable radios.

[Steve Conner]

And a lot more fun to test with your tongue, too!

I've used the Coilcraft HPH5-0155 as a kind of multipurpose flyback transformer with the LM2586. It has 6 independent windings, all the same number of turns, so you can configure it up to a 1:5 ratio. That would get you 200V or more.

There's also the low frequency approach with an iron cored transformer. Here's a good example of this type of inverter:
http://www.dos4ever.com/battery/battery.html

Higher powered versions were popular in mobile tube radio transmitters, going by the generic name of Royer or Jensen oscillators.

[soundguruman]

"And a lot more fun to test with your tongue, too!"
Go ahead and prove how brave you really are. Test THIS!
I have to remember testing batteries that way is really a bad habit.

[iccaros]

thanks for the link Steve, I will need to study.. I was thinking of a 7404 inverter using simple transistors for current to a 9v:100v transformer.. but This looks like a better design. I messed with this designMAX1044 / ICL7660S High Voltage SMPS Experiment - don't try this at home!, giving me 100V using a 50R and a IRF740, and 200uh.
I attempted this one last night http://www.sm0vpo.com/power/vconv_01.htm, but I do not have 557, only c9012 and c9013 as the closest matched npn pnp combo, which I could not get to oscillation.

[iccaros]

@imaradiostar
Thanks, I have been reading a lot of R.G.'s stuff

[J M Fahey]

"And a lot more fun to test with your tongue, too!"
Go ahead and prove how brave you really are. Test THIS!

I see you missed the >>><<< that accompanied Steveīs post.
Maybe you should a little more.
Are we having a bad hangover today?

[Steve Conner]

The wasn't a "Shut up", it was a tongue bandage.

I speak from experience as I tested one of those B+ batteries with my tongue at an early age. A 67V one the size of a juice carton. Luckily it was pretty old and worn out, but I still remember the experience and it taught me some respect for high voltage, not to mention that it put me off licking any sort of battery for life.

[J M Fahey]

Then you are "brave enough"
They always say those Kilts hide "something" , glad to know itīs true.
In an indirect way, of course