On 1/5/19 11:45 AM, seymour.shabow wrote:
> LexingtonVAPin wrote:
>>
>> There are two flipper diodes on both coils.
>>
>> My knowledge on design / theory of coils & solenoids is limited. Not
>> sure how parallel vs. serial would dictate number of diodes. Please
>> explain.
>>
>
> One diode for each coil contained in the bobbin, for reverse voltage
> protection. Also, count the # of wires coming out - there's 4. 2 coils.
In the color me dense dept (and I don't have an early Williams coil
handy): it appears that the FH WPC is connected differently. The power
is going to the common (two wire lug). The EOS switch completes the
power winding circuit. When the EOS switch opens, the power winding is
disconnected. The hold winding is always powered. Since they are run
in parallel, each winding needs it own diode. Each winding's field
collapses at different times.
On the 6MDM, the power is to one of the two windings (single wire).
When the EOS is closed it shorts out the first winding (hold) and the
power runs through only the power winding. When the EOS is open, it no
longer shorts out the hold winding and the power runs through both
coils, in series.
In this case, I think that only one diode could be used, since the
windings are connected in series. Both windings' fields collapse at the
same time.
It is not clear to me why Williams stopped using the EOS to short out
the hold winding and started using it to disconnect the power winding.
Maybe in that application, the capacitor is more effective?
>
>> I had always believed that all early flipper coils were series until
>> Clay raised this question. If he is right, there is a lot of
>> misinformation out there.
>
> All WILLIAMS early flipper coils are.
>
>>
>> "The [WILLIAMS] parallel wound coil was first used on F14 Tomcat and,
>> in conjunction with a capacitor, greatly reduces the arcing on the EOS
>> switch (instructions for upgrading can be seen below)."
>>
>
> [EMPHASIS ON WILLIAMS] coil added. Clay's guides (especially out of
> date bootleg ones) are/were evolving documents - and they are
> 'compartmentalized' in that any information in them is assumed to apply
> to JUST that manufacturer's equipment, unless specifically specified
> otherwise. Clay discouraged people from backing up/printing out the
> guides - I did myself before they were removed from the web and even in
> that short time, lots of information changed. Atari flipper coils
> appear to be parallel wound as well... Gottliebs, nope.
My quote does not come from Clay's guides. That comment about F-14
being the first to use parallel seems to be common across the web.
[If it is on the web, it must be true.]
>
> You can tell if there are 2 coils in there - unsolder the wires from the
> lugs and measure each. You won't find continuity between more than the
> 2 coils. If I have another hosed flipper coil somewhere I'll unwind
> another one and take pictures this time, or just take one again for the
> team - it's not like I don't have boxes and boxes of this stuff laying
> around. (I do....) >
> LMK if you want me to take a coil apart and I'll film the results.
It would be nice to take apart 3 different coils: WPC, early Bally,
early Williams. Are you a glutton for punishment? :-)
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