[ARC5] Dynamotor Capacitor

[Bruce Long]

it seems to me the original ARC designers did not select the dyno bypass capacitor voltage rating on the basis of the largest amplitude voltage spike that could be generated by the receiver dyno but rather from the largest spike that could be created, typically a load dump spike- that could be generated by any large 28vdc load on the aircraft 28vdc buss.

I can't say I have a detailed knowledge of WW2 28vdc power systems but I think the load dump spike from a prop pitch motor or the aircraft engine starter motors coudl be really impressive.

As a partial reality check i think I remember the design standard for 12vdc automotive electronics is to resist 600 volt load dump spikes.   I think there is an old National applications sheet or data sheet for one of they 12vdc automotive service IC audio amplifiers that has a discussion of the largest voltage spikes that can be expected in a 12vdc automobile buss.

If my memory is correct, then a 2kv rating for the arc-5 receiver 28v bus bypass is not out of line.

We are talking about the 28vdc bypass?   I have been sorta following this discussion as I do other work.





On Tuesday, March 25, 2014 6:15 PM, Kenneth G. Gordon <kgordon2006 at frontier.com> wrote:
 
On 25 Mar 2014 at 19:35, Fuqua, Bill L wrote:

>   One thing that I have not seen addressed.
> That under real conditions it is not a matter of one dynamotor and radio being
> connected to a battery, but a number of loads connected to a battery and with
> various impedances, perhaps their own brushes and dynamotors, etc.

Well, I did mention that, in fact. I made the point that when we are operating 
this gear stand-alone, we would more than likely not see such impressive 
spikes.

Ken W7EKB

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