Re: MOT Voltage Doubler

To: tesla-at-pupman-dot-com
Subject: Re: MOT Voltage Doubler
From: Marco Denicolai <marco-at-vistacom.fi> (by way of Terry Fritz <terryf-at-verinet-dot-com>)
Date: Mon, 21 Sep 1998 06:27:30 -0600
Approved: terryf-at-verinet-dot-com

At 12:08 20/09/98 -0600, you wrote:
>Original Poster: "David Dean" <deano-at-corridor-dot-net> 
>
>
>
>>Original Poster: "Gregory R. Hunter" <ghunter-at-enterprise-dot-net>
>>
>>Dear List,
>>
>>I've been studying the half-wave voltage doubler circuit (MOT, cap,
>diode)
>>found in US-type microwave ovens, and I think I understand how it
>works.
>>What is the ultimate voltage developed by this thing.  Looks like 2.8 x
>>RMS.  Is that it?  If I'm correct, then it doesn't really "double"
>anything
>>does it?
>>
>>Greg
>>
>>
>nope. It is a simple half wave rectifier. It is not a voltage doubler.
>The topology is a little strange however, in that the diode is grounded
>on one end shorting the positive going half cycle. The negative going
>half cycle
>is conducted to the K (cathode or heater) of the magnatron by the
>capacitor.
>The capacitor is not used as a filter or as an energy storage device.
<SNIP>

No. The circuit used in microwave ovens IS a VOLTAGE DOUBLER. The
topology
is "a little strange" just because it is NOT simply an half wave rectifier.
In the
microwave oven (with no load) its peak output voltage is:

Vpeak = VMOT_peak*2 = VMOT_RMS*1.4*2 = VMOT_RMS*2.8

that is a pulsed (50/60 Hz) voltage going from 0 to 4kV*2.8 = 11.2 kV.



________________________________________________________________________

 Marco Denicolai                   Vista Communication Instruments, Inc.
 Hardware Development Manager      www.vistacom.fi   

 marco-at-vistacom.fi                 Kaisaniemenkatu 13 A
 fax:    +358-9-622-5610           SF-00100 HELSINKI
 phone:  +358-9-622-623-15         Finland

   Remember, Murphy was an optimist! I am not...
________________________________________________________________________