DC to AC Converter.....400 Hz?

To: tesla-at-pupman-dot-com
Subject: DC to AC Converter.....400 Hz?
From: gweaver <gweaver-at-earthlink-dot-net> (by way of Terry Fritz <twf-at-verinet-dot-com>)
Date: Sun, 28 Mar 1999 11:40:49 -0700
Approved: twf-at-verinet-dot-com
I have seen several of those 400 HZ generators for sale. I have no
experience with 400 Hz generators.  I was wondering if they are like most
generators they have an RPM rating.  If you run a 400 HZ generator 6.666
times slower than the rating will it produce 60 HZ and will the power output
be less also?  I could probably connect a DC motor to a generator and it
should run without making much noise.  A sound proof enclosure would help
reduce noise.

Gas engine powered generators make too much noise.  I would need a 200 yard
extension cord to get the generator far enough away to hear the TC running.
That doesn't make sence to me.  

I drew up a circuit using 2 SCR's to produce 60 HZ 120 VAC 1500 watts.  I
like to use what I already have in my junk box if I can.  I already have a
1500 watt 10:1 transformer, several 400 amp 600 volts SCR's.  The driver
circuit is 120 volts 60 HZ from a 12 VDC car battery, I hope it will drive
the SCR's.  I am planning on building a prototype today if I get time.  I
don't have much experience with SCR's, I figure its never too late to learn
something new.  I am not sure if the drive is worth using but its OK to
experement with for now.  The drive I am using is the circuit I got off of
the web that is suppost to produce 120 VAC HZ 300 watts from a car battery
but it really produces 120 VAC 60 Hz 60 watts output. I don't know how much
voltage or power it takes to turn ON/OFF an SCR.  Maybe a 555 timer will
work for an SCR driver?  I have the SCR's connected to the input of the 1500
watt transformer, they turn on/off one at a time, one SCR pulses the
transformer positive and the other SCR pulses the transformer negative, 60
times a second each.  The output will be 60 HZ, not exactly perfect sine
wave.  My battery is rated 750 amp hours, I should be able to get 62 amps
out of it for a few minutes with no problem.  

Gary Weaver




>Tesla List wrote:
>
>> I too would be interested in a inverter design. I believe this is on-topic,
>> for any coilers wanting to do remote coiling. Commercial inverters are
>> going to be $400+ for 750 watts or more. Generators, are realistically the
>> most economical...
>
>Seems like this would be a perfect application for some of these 400 hz
surplus
>generators you see for sale for essentially scrap value.  400 hz should go
>through a pig just fine (don't know about NST).  C&H sales has several large
>400
>hz machines cheap (http://www.candhsales-dot-com)  That and an el-cheapo car motor
>would do the trick for far less than what an inverter would cost.  400 hz
>motors
>are dirt cheep too.  A 2 pole motor would really make a rotary gap sing! 
>That'd
>be 24,000 rpm.
>
>The compact car motor trick is very viable.  I built a 20 kw 60 generator for
>my
>catering wagon (I own a restaurant too) using a surplus generator and a toyota
>corolla motor.  The motor will pull the load at 1800 rpm and is as quiet as a
>sewing machine.  This one has an electronic carburator and I was able to use
it
>to tune the engine for the best economy.  I paid $200 for the engine and
tranny
>(to have something to hook the starter to) and all the support equipment
>(radiator, etc) delivered to my shop.
>
>--
>John De Armond
>johngd-at-bellsouth-dot-net
>Neon John's Custom Neon
>"Bendin' Glass 'n Passin' Gas"
>
>
>
>