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JC-80 eBay PCBs
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Old 11th November 2011, 05:14 PM   #21
Wolfsin is offline Wolfsin  United States
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Assuming 22 ohm Caddocks, I can (by ordering for qty=2 PCBs) get the parts and PCBs for $80/channel aside from the J74 / K109. Since I already have a matching pool of those it is hard to guess what the cost might be to j-random fanatic.

A quick run down of the BOM (without revealing it) is Holco 1% non-magnetic resistors, Nichicon Muse KZ & ERO MKP caps, and a sufficient assortment of SMD resisors for the servo to allow matching. The one advantage a 'lone Wolfsin' has is the time to carefully match parts.

The only 'original Toshiba' are the singletons so if other components need special consideration, please raise a red flag. I am satisfied with that level of expense but feel certain that a GB could result in $75 JC-80s -- a price point at which I would expect considerable demand.
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Old 11th November 2011, 05:43 PM   #22
simon7000 is offline simon7000  United States
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Dale CMF60 or similar brown colored Dale resistors are an inexpensive high quality resistor. Both Digikey and Mouser carry them.

At 18 volts or so above 20,000 ohms 50 PPM tempco should be fine. 25 PPM for lower values if you are fussy.

Above 100K you might consider the standard Xicons.
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Old 11th November 2011, 06:21 PM   #23
Wolfsin is offline Wolfsin  United States
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Quote:
Originally Posted by simon7000 View Post
Dale CMF60 or similar brown colored Dale resistors are an inexpensive high quality resistor. Both Digikey and Mouser carry them.
The Holco are equivalent I think. Dale custom assortment could be had at additional shipping of $4 or ordering from DK or Mouser for about $6 more shipping. So it is $10, $14, or $16 for the thru-hole resists for two channels.

Not sure how to interpret non-quoted part of post, @simon7000
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Old 11th November 2011, 06:40 PM   #24
john curl is offline john curl  United States
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Trust Ed Simon, I do.
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Old 11th November 2011, 08:46 PM   #25
Wolfsin is offline Wolfsin  United States
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Default Thanks for the QC, John

Let me take a stab at what that earlier post was meant to communicate. Please correct if I stray. Matching is good but temperature coefficient must be considered as well, especially for low resistance values (most of the thru holes) or operating at voltages less than 18 volts (i.e. the entire servo section SMDs). Thus it might be necessary to make finer distinctions than merely SMD & thru hole as in the BOM.
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Old 11th November 2011, 09:38 PM   #26
john curl is offline john curl  United States
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Tempco with a JC-80 is not very important, because of the servos.
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Old 12th November 2011, 12:02 AM   #27
john curl is offline john curl  United States
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It is not a good idea to recommend Holco resistors that are not made anymore.
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Old 12th November 2011, 12:27 AM   #28
tomtt is offline tomtt
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Has "Sponge Bob" succeeded again?

sponge bob has been brought under control ...


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Old 12th November 2011, 12:42 AM   #29
Wolfsin is offline Wolfsin  United States
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First a reprieve on the SMDs and now keeping Wolfsin from falling for his 'cheap side'. You are really too good at this! Agreed that adding unobtaniums to the BOM is very poor form.
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Old 12th November 2011, 10:39 AM   #30
Wolfsin is offline Wolfsin  United States
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Default Housekeeping

I am down to three items that I cannot fully spec on Mouser or DK. 1)dual JFETs discussed earlier will be matched/built with singletons, 2)2SK2013 & its complementary are modestly priced on eBay, 3)tubular caps C2 & C3.

The pair of axial tubular caps marked C2 and C3 on silk screen parallel the electrolytics to ground on the 24v rails. The BOM description is insufficient to identify the part on DK. Would this ideally be polypropylene? Is the value critical?
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