[sdiy] Reason Eight (was discharging...^)

[Bob Weigel]

Harry..I have various types of resistance wire. Don't trouble yourself.  
-Bob

Harry Bissell Jr wrote:

>Ok I confess... I do not usually discharge
>voltage circuits.  I have bleeder resistors that
>take them down safely (all by themselves)... 
>
>I have been sorry (occasionally) when I work on
>someone
>else's design and  allow the PCB to contact a metal
>object (could it be... a screwdriver on the bench) ???
>
>I'm re-doing the capacitor experiment where I short
>the
>cap and record the voltage / current.  I have a big
>box of 1500uF / 35V caps (so I can get a fresh one)
>and my
>AC current probe, and a digital scope.
>
>I'll make photos available of the results. You will
>see
>discharges that occur from a single pulse to many
>distinct pulses... all via arc discharge.  If someone
>wants to host them (for a while) let me know and I'll
>send them to you.  
>
>Bob... I have an idea for you. I could send you some
>nichrome wire that you could wrap around the shaft of
>the screwdriver. You'd get a couple of ohms of
>resistance... enough to take the brunt of the
>discharge. It will still snap a little bit.  (I
>thought
>of some antistatic foam but that is WAY too high in
>resistance to be practical.
>
>
>
>--- Bob Weigel <sounddoctorin at imt.net> wrote:
>
>  
>
>>Personally..I never discharge caps in LV circuits. 
>>:-)  I'll leave that 
>>headache to those who do. -Bob
>>
>>harrybissell wrote:
>>
>>    
>>
>>>Another reason to add to the list...
>>>
>>>8)  If the circuit uses voltage regualtors (78xx,
>>>      
>>>
>>79xx) and the circuit
>>    
>>
>>>designer did not READ the data sheet carefully and
>>>      
>>>
>>provide the reverse
>>    
>>
>>>diode
>>>across the input and output terminals... 
>>>      
>>>
>>discharging the capacitor by
>>    
>>
>>>short
>>>circuit WILL destroy the regulator.
>>>
>>>H^) harry
>>>
>>>
>>>
>>> 
>>>
>>>      
>>>
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