All tube inverter from batteries?

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All tube inverter from batteries?

Postby Austin Translation » Wed Aug 10, 2011 10:10 am

Would it be easy to make a tube inverter? I know I could go to harbor freight and get one for $14.99 but out of curiosity couldn't an inverter be made from only tubes somehow if you just wanted to? Like an oscillator hooked to a transformer right? I don't want to use a mechanical vibrator, are there any tubes that could pass enough current at 24v to make any useful amount of juice on the other side of the transformer? I'm researching it Just thought I'd ask you guys to get some feedback. Thanks, Austin
Last edited by Austin Translation on Thu Aug 11, 2011 1:14 pm, edited 1 time in total.
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Postby EWBrown » Wed Aug 10, 2011 1:57 pm

Other than perhaps some thyratrons or gas controlled rectifiers, there are no suitable tubes out there for your described application. Low voltage high current tubes are a virtually non-existant. Low plate voltage trubes generally run at low power, only 10-20 mA max. plate current.

The best way to go is with solid state, it is efficient, quietn and can handle high power. I bought a military surplus DC to AC power invertter about ten years ago, which takes in 24 to 36VDC, and outputs a very clean, crystal-controlled, sine wave 120VAC @ 60Hz, at up to 1500 VA continuous, and 2500 VA intermittent service The unit senses the AC load and kicks in the appropriate number of power transistors to maintain peak efficiency. Yeah, it's big and heavy.

The little cheap inverters like from Harbor Freight and car parts stores are cheap and cheesy, and output a rather nasty stepped square wave, which is OK for most resistive loads, but would not be the best to power up a tube amp. This is a definite good example of getting just what you pay for...

Dynamotors and vibrator power packs are noisy and inefficient, a dynamotor would probably drown out the sound of all but the most powerful amps, they sound like small jet engines, when they spool up.

/ed B
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Postby Austin Translation » Wed Aug 10, 2011 9:19 pm

Thank you for the reply. I think the best and easiest bet is to just use my four 18v dewalt batteries connected in series for 72v b+ to build a battery tube amp. Im trying to make a 12dw7 mini amp for playing my electric guitar at acoustic outdoor jams and I think it would be nice to have a tube amp running on batteries.
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Postby burnedfingers » Mon Aug 15, 2011 4:15 am

Thank you for the reply.I think the best and easiest bet is to just use my four 18v dewalt batteries connected in series for 72v. Im trying to make a 12dw7 mini amp for playing my electric guitar at acoustic outdoor jams and I think it would be nice to have a tube amp running on batteries.



Buy a portable generator to power your equipment.
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Postby Austin Translation » Mon Aug 15, 2011 8:18 pm

Yeah I need a good generator, they are spendy and loud tho. I have solar panels, maybe i could do something with them.
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Postby 20to20 » Tue Aug 16, 2011 11:41 am

Im trying to make a 12dw7 mini amp for playing my electric guitar at acoustic outdoor jams


Any input is appreciated, Thanks~ Austin


Doesn't this kind of go against the principal of an "acoustic" outdoor jam?

If all you want to do is just get your electric out there in the woods I think a decent inverter on 2 car batteries would get the job done. The fact that an inverter might not create perfect sine power I doubt would color the guitar amp output in such a way as to be noticable. This ain't a HIFI application.

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Postby Austin Translation » Tue Aug 16, 2011 1:31 pm

Yes it works to use the inverter to run my tube amp, the amp is THD Univalve and is silent even tho its a cheap inverter. But all I learned was that it works! The whole point of any of this effort that I spend is to gain as thorough of an understanding as I can. I guess the easiest way (to answer my own question) is to simply buy 100 rechargable aa batteries and sting them all together in series for the b+ power supply. I already have 4 18v drill batteries so maybe I will use those. Li-ion would be obviously the best but money is also a factor. I am trying to build an amp that runs on batteries so I can walk around with a tube amp running on batteries that can be my guitar amp. The amp is needed for acoustic jams because I don't like playing acoustic guitar and at drum circles to be loud enough to be heard. Next after this I plan to build a linear amplifier for short wave radio or cb that runs on batteries. If I can figure out a dc coupled amp design, then it will be linear from dc to in the mhz range and I could maybe even use the same amp for both purposes which I think would be really cool. Have a guitar amp that could also function as a linear amp! Solar panels! I bet with cathode bias to compensate the change in volts when the clouds come the solar panels could make enough juice for b+ without any batteries helping at all except for filaments!http://home.comcast.net/~stphkeri/Bates_DirectCoupledCathFollower.pdf

this amp only needs 53 milliamps for b+, a decent battery source could run for days on that little of a drain. Years ago battery powered tube radios in cars even battery powered tube walkie-talkies were very popular as I understand! I know I can do it and that it will be awesome. Thanks, Austin
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Postby mesherm » Tue Aug 16, 2011 2:36 pm

http://www.dos4ever.com/battery/battery.html

This link should give you some inverter ideas.
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Postby Austin Translation » Tue Aug 16, 2011 6:02 pm

Great link! Thank you
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Postby 20to20 » Tue Aug 16, 2011 10:12 pm

You could use a battery powered Sony Walkman tape recorder with a 60hz signal recorded from a test signal CD to drive your inverter.
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Postby Austin Translation » Wed Aug 17, 2011 12:28 am

"Interestingly enough it turns out that square waves, and quasi-sine wave pulse width modulated stepped rectangular waveforms, make better sources for rectification into smoother more ripple free DC voltage than do sine waves. The reason is that these "flat-topped" waveforms as I call them have a higher average output voltage value and the output voltage is at peak value longer than for "round-topped" sine waves. All engineers know that the charging of a DC power supply occurs at the peak of the waveform. Thus, since flat-topped waveforms are at the peak longer they keep the DC supply input fully charged longer and thus the DC output is smoother. This reduces ripple and improves the system power factor. This can be easily demonstrated by attaching an oscilloscope on the output of a DC power supply and observing the ripple with a sine wave input and then a square wave or stepped waveform input, all of equal RMS value. The DC is smoother with the flat-topped waveforms than for round-topped sine waves."

as taken from http://www.kerchner.com/electrical/sinewave.htm

Seems like this might suggest that a cheap $15.99 inverter might not be so bad as a power supply.
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Re:

Postby TonyWells » Thu Dec 05, 2013 1:01 am

Austin Translation wrote:Yes it works to use the inverter to run my tube amp, the amp is THD Univalve and is silent even tho its a cheap inverter. But all I learned was that it works! The whole point of any of this effort that I spend is to gain as thorough of an understanding as I can. I guess the easiest way (to answer my own question) is to simply buy 100 rechargable aa batteries and sting them all together in series for the b+ power supply. I already have 4 18v drill batteries so maybe I will use those. Li-ion would be obviously the best but money is also a factor. I am trying to build an amp that runs on batteries so I can walk around with a tube amp running on batteries that can be my guitar amp. The amp is needed for acoustic jams because I don't like playing acoustic guitar and at drum circles to be loud enough to be heard. Next after this I plan to build a linear amplifier for short wave radio or cb that runs on batteries. If I can figure out a dc coupled amp design, then it will be linear from dc to in the mhz range and I could maybe even use the same amp for both purposes which I think would be really cool. Have a guitar amp that could also function as a linear amp! solar panels! I bet with cathode bias to compensate the change in volts when the clouds come the solar panels could make enough juice for b+ without any batteries helping at all except for filaments!http://home.comcast.net/~stphkeri/Bates_DirectCoupledCathFollower.pdf

this amp only needs 53 milliamps for b+, a decent battery source could run for days on that little of a drain. Years ago battery powered tube radios in cars even battery powered tube walkie-talkies were very popular as I understand! I know I can do it and that it will be awesome. Thanks, Austin

Glad you shared such useful information..I have been thinking of using similar inverter system and hope it works out wel.. I would love to contact you and please guide me out.
Last edited by TonyWells on Fri Dec 06, 2013 9:42 am, edited 1 time in total.
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Re: All tube inverter from batteries?

Postby EWBrown » Thu Dec 05, 2013 10:13 am

I've used some of the Triad TY-xx series of toroidal inverter transformers in various 12V to 300 and 600VDC power supplies for ham radio projects in the past, they operate about 2 KHz square wave, and are very efficient, and need only a relatively small B+ filter cap - 10 uF is usually plenty. Only downside was a 2 KHz "whine", which was tolerable for radio transmitting, but would quickly become wearisome in an audio application.

50-60 Hz power transformers may tend to get "ringy" when fed with a square wave (of any frequency), but, as they say, no pain, no gain, it could work well for a portable / mobile tube amp, but then it could be kinda "buzzy" too.

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