Re: Remote Power Supply Connection

Trevor Wilson wrote:
> "Ian Thompson-Bell" <ruffrecords@[EMAIL PROTECTED]
> wrote in message 
> news:g16ked$1r7$1@[EMAIL PROTECTED]
>> Trevor Wilson wrote:
>>> "Ian Thompson-Bell" <ruffrecords@[EMAIL PROTECTED]
> wrote in message 
>>> news:g13o17$10ph$1@[EMAIL PROTECTED]
>>>> Trevor Wilson wrote:
>>>>> "Ian Thompson-Bell" <ruffrecords@[EMAIL PROTECTED]
> wrote in message 
>>>>> news:g0up1a$1ap1$1@[EMAIL PROTECTED]
>>>>>> Trevor Wilson wrote:
>>>>>>> "Ian Thompson-Bell" <ruffrecords@[EMAIL PROTECTED]
> wrote in message 
>>>>>>> news:g0rmo0$27co$1@[EMAIL PROTECTED]
>>>>>>>> I agree when the rectifiers are close to the transformer
supplying 
>>>>>>>> them but not when they are separated from it my a couple of
metres 
>>>>>>>> of cable.
>>>>>>> **And again, it is not difficult, nor expensive to deal with such 
>>>>>>> issues. A handful of capacitors will effectively deal with any 
>>>>>>> problems.
>>>>>>>
>>>>>>>
>>>>>> Definitely not. The point is that the caps normally used to
suppress 
>>>>>> reverse spikes in semiconductor diodes do just that. The have no 
>>>>>> effect on the forward current spikes which are significant.
>>>>> **No.
>>>>>
>>>> Denial is not much of an argument.
>>> **How about: Not necessarily? Better?
>>>
>> Hardly.
>>
>>>>>  With remote ac
>>>>>> supplies these current spikes must pass through the cable and they 
>>>>>> will cause serioes radiation. Any attempt to stop them happening
will 
>>>>>> simply stop the rectifiers from rectifying. That is why is is 
>>>>>> essential to have the rectifiers close to the transformer.
>>>>> **No.
>>>>>
>>>> Denial is not much of an argument.
>>> **OK. It is not necessary to have rectifiers close to the transformer.
I 
>>> set up a test last night, with 2 Metres of cable, connected to a 
>>> transformer, thence to a rectifier, thence to an amplifier. An AM
radio 
>>> place VERY CLOSE to the cable picked up some radiation. Covering the 
>>> cable with an earthed sheild completely eliminated the noise.
>>>
>> And what current were you drawing from the rectified output?
> 
> **4 Amps @[EMAIL PROTECTED]
 60 Volts.
> 
> 

That's a decent load. I am not completely convinced though. First an 
a.m. radio covers only a limited bandwidth from about 500KHz to 1MHz and 
I would expect fast rectifier spikes to produce spectrum well beyond 
that. Secondly, an earthed ****eld only eliminates the electric field. 
The magnetic field will see that as transparent. Have you tried it with 
an air band receiver?


Cheers

Ian