JJ,
Do you have an isolation transformer you can connect to your variac? As
suggested, the neutral wire is grounded at the panel or the service
entrance. You need both AC sides of the bridge to float connected to a
variac.
Jim Mora
-----Original Message-----
From: Tesla [mailto:tesla-bounces@xxxxxxxxxx] On Behalf Of jj@xxxxxxxxxxxxx
Sent: Thursday, August 28, 2014 7:58 PM
To: Tesla Coil Mailing List
Subject: Re: [TCML] overheating diode strings
I again checked the strings on each bridge and they are all correct as
per the schematic. For the record the diodes are"10A 1000V MIC 10A10
High voltage diodes". Both bridges have the same problem. Could it be
the diodes?
On 8/28/2014 8:31 PM, David Speck wrote:
> Jim,
>
> Your schematic should look something like the following, with a whole
> lot more diodes:
>
> (AC Input)
> |
> |--|>|--|>|--|>|--|--|>|--|>|--|>|--|
> | |
> | (-) | (+)
> | |
> |--|>|--|>|--|>|--|--|>|--|>|--|>|--|
> | | |
> (Negative) (AC Input) (Positive)
> (output) (Output)
>
> I'd guess you have one leg of the bridge turned around.
>
> Dave
>
>
> On 8/28/2014 7:00 PM, jj@xxxxxxxxxxxxx wrote:
>> Hello Everyone,
>> I constructed eight strings of 50, 1000V, 10 A diodes. I assembled
>> and tested four strings without equalizing capacitors and resistors
>> and four strings with equalizing capacitors and resistors.The diodes
>> came off eBay from a company in China. All diodes checked OK on my
>> diode tester. These strings were then soldered into two full wave
>> bridge rectifiers powered by a variac. My scope shows a 60Hz output
>> on both which should be 120 hz output. The negative output string
>> that connects to the wiper of the variac becomes too hot too touch at
>> less than 5 volts output on both units. One of these when working
>> properly will be supplied by an 8 Mot stack.
>> All help will be greatly appreciated.
>> Thanks, Jim
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>>
>>
>
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