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Demon 2C

Posted: Mon Dec 19, 2016 8:51 am
by bluewormx
I just picked up a Schumacher C-car, and it came with this beauty from 1981.
Before my time I started racing in 1985, My first speed control was a Demon king 6x BUZ11 fets although I recall upgrading it to proking spec by installing the other 2 fets.

I had a buddy whom had the older Demon 2DH which was probably the buggy version of the 2C because it had at least 2 relays if not 3.

I re wired the power cables in the last photo. I did slso change the servo wire this morning. Still waiting on some heatshrink to wrap it with as they where back in the day.

It works great! :D

Re: Demon 2C

Posted: Mon Dec 19, 2016 8:58 am
by bluewormx
Here with the power cables changed.

Re: Demon 2C

Posted: Tue Dec 20, 2016 5:00 am
by bluewormx
Here with new servo wire, ready for Heat shrink. :D

Re: Demon 2C

Posted: Tue Dec 20, 2016 10:58 am
by tamiyadan
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Re: Demon 2C

Posted: Tue Dec 20, 2016 6:46 pm
by bluewormx
Dan, I really thought that the early Tekin and Novak speedos where SMT because of how small they are compared to the British speedos of the time: Demon, Laser, Black box etc...
After seeing the circuit topography of your Tekin I am truly amazed that they are through hole and how well layed out the circuit is. Like you said a work of art.
The first British speedo of a comparable size to those early US ones that I saw where prototype Schumacher ones, it must have been early 1988 it was heatshrink wraped and did feature a two layer SMT design. Both in the Schumacher SPC cars of team drivers: Phil Davis and Andy Smith.

The speedo that really caught my attention was the Corally MMS (the credit card speedo) A work of art at only 5 or 6mm thick. (1/12th version). Never did I see one in the flesh...

Re: Demon 2C

Posted: Tue Dec 20, 2016 10:28 pm
by tamiyadan
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Re: Demon 2C

Posted: Wed Dec 21, 2016 9:23 am
by V12
The Demon 2C was Nick´s second generation ESC. There were several variations where the main difference was size of relays and size of heatsink plate. I think all of these ESCs were based on the 2C PCB and using one relay for bypassing the transistor at full throttle for lower voltage drop. If you got a Reverse version of this ESC there will be another relay. I´m not sure if there was another version using three relays but I could ask a friend who maybe knows more than me.

The 2DH was the buggy version and I think the name maybe means double height as the relays were much larger. The 2DH was quite a sturdy ESC and very popular in offroad cars, even when the FET ESCs were available.

The Demon 1 and 2 were Nick´s first generation ESC which came without the bypass relay as ESCs of other manufacturers. The bypass relay circuitry was introduced later as a addon, known also as turbo relay.
If you´re interested in early ESC you can find several at https://classicrc.wordpress.com/

Re: Demon 2C

Posted: Wed Dec 21, 2016 4:54 pm
by bluewormx
This 2C has the bypass relay underneath the heatsink between the power transistors.

The Proking in my opinion was crippled by the reverse relay and the weak braking power transistor TIP 36A, I blew more tha one.
The reverse relay used the NC (normally closed) contact for forwards so having x8 BUZ 11 rated 240A continous current passing through a 25A contact was not ideal. The easy fix was to remove the relay, hardwire it on the PCB and go forwards only.
Later prokings had a second power transistor shoe horned on top which mitigated that problem.

Non the less they where very good speed controls.
In fact I like them so much that I'm trying to hunt one down...

Re: Demon 2C

Posted: Wed Dec 21, 2016 6:01 pm
by V12
The TIP 36A is a Darlington and not really a powerful transistor, my early ESCs used BD250 which were much better.

The problem with relays is, there is none which really could handle the power of the FET transistors when using a 4WD car or a very hot motor, at least not at that size. You sure could find matching relays but they would be as large as the car. :lol:
I think none of the reverse ESC was intended for racing. The relay contacts will go worse through use and will affect the voltage drop across the ESC badly anyway. Most of the relays are not dustproof what is another problem, at some point I found airtight relays (made by SDS) which could handle the amp draw of 1/12 scale cars and my early RC10. This was for my pre-FET ESC where we used 19T motors as a max.

Re: Demon 2C

Posted: Wed Dec 21, 2016 6:24 pm
by bluewormx
This Demon 2C has BD249 as the forward transitor snd a BD250 for brake. Why would nick switch to TIP 36A? was it simply cheaper? He charged me 5 quid each and I'd change them myself.

V12 I have a million questions for you. I feel like a little kid again "Daddy where do babies come from?"

I'll try keep it on topic.

Do you have any photos of your own speedos? I would love to see them.

What where the two nasty big schottky diodes on the input and output of the Proking for? simple crowbar to protect on reverse polarity or some other function?

Where did you race? I raced at club Heathrow 1/10th and 1/12th, Watford 1/12th. I also raced at many other places maybe once or twice: Oaks park, Eden park, Chesington, Hampton, Cranford, and Romsey once.

Re: Demon 2C

Posted: Tue Jan 10, 2017 11:39 am
by bluewormx
IMG_1363.JPG
The heatshrink finally got here. Slow boat "from" China ;)
I put Corally style connectos on the battery wires, these really aren't period correct since they did not appear until about 1987.
I guess its done now. :D
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Done is never done...
I re-applied the heatshrink in the other direction
seems like a better fit.

Re: Demon 2C

Posted: Sat May 22, 2021 9:26 pm
by dinglem
Hi Francis, just throwing mine up for comparison... although it looks to be identical apart from mine having a slightly larger plate.

1981 dated Demon 2C 'ISS B', which is in surprisingly good condition. I also have an 'ISS C' dated 1982 which differs only by having a full width upper plate - not sure what the B to C difference indicates? The small round sticker has 780 240 hand-written on it, the latter part dating it as actually being made in week 40 of 1982.
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Here's the other one (with the full sized upper plate present and removed) for reference.... it has a white pot too!
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Re: Demon 2C

Posted: Sat May 29, 2021 6:34 am
by bluewormx
IMG_3854.JPG
I finally re-heatshrinked mine again and had a peek at the date and serial number.

831 -243, Number 831 1982 week 43

I'm pretty sure the Demon 2C was probably the second most built after the proking which I have seen go into the low thousand. I wonder how many Novak 1's where made 10's of thousands at a guess... :D

Re: Demon 2C

Posted: Sat May 29, 2021 10:28 pm
by dinglem
Interesting dating and unit number comparison there if you think about it.

Mine was unit number 780 from week 40, and just 3 weeks later yours was unit number 831. So 51 units between them. I am guessing Nick wasn't making various speedo models at this stage, but even if he was that is quite some number of units to churn out in a short period of time!!

it is quite cool that we have the code for the sticker dating 8)