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Demon 2C

esc's, charger's, batteries....

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bluewormx
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Demon 2C

Post by bluewormx » Mon Dec 19, 2016 1:51 pm

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
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Last edited by bluewormx on Tue Dec 20, 2016 11:48 pm, edited 1 time in total.

bluewormx
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Re: Demon 2C

Post by bluewormx » Mon Dec 19, 2016 1:58 pm

Here with the power cables changed.
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Re: Demon 2C

Post by bluewormx » Tue Dec 20, 2016 10:00 am

Here with new servo wire, ready for Heat shrink. :D
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tamiyadan
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Re: Demon 2C

Post by tamiyadan » Tue Dec 20, 2016 3:58 pm

cool :D

yup offroad was a real issue all through the ESC first generation era. the amp load was much much higher then onroad and the dirt and water in offroad got in everything and either stuck relays or shorted everything out.

the early offroad had more relays since they were usually sealed and could take more current these acted like a MSC but the resistance was electronically controlled and gummed up less then a wiper arm.

there are various designs. i have seen 2 steps with a variable range in the center. the tamiya Hilux transistor ESC works kind of like this. if you had reverse then it was a 3 relay version.

you had a relay or microswitch kick off a very low speed that crawled then it would kick off into a proportional throttle through the transistor or single mosfet and then kick off again to full power.

before 1986 you pretty much got creative with the MSC making something between a msc and esc.

in the days before 1986 ESC were basically a toy of onroad 1/12 pan cars, where they ran 4-5 cells the cars were light and the current draw low.


early ESC are magical :D


it makes kevin's delta autodrive in 1984 really revolutionally and game changing that first autodrive basically paved the way for the next 20 years of ESC design that did not change much in basic principle.

the autodrive was designed to fit right in the center of the delta 1/12 pan chassis between the batteries.

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Re: Demon 2C

Post by bluewormx » Tue Dec 20, 2016 11:46 pm

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...

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tamiyadan
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Re: Demon 2C

Post by tamiyadan » Wed Dec 21, 2016 3:28 am

yeah amazingly everything in from the first to third generation is though hole

Novak first and second generation Novak, Novak 1, Novak 4, Novak T-X series is all through hole, the first 3 are single sided boards, the T-series starts double sided board construction.

the next generation esc went SMT and microprocessor High frequency, the first MX used off the shelf stuff, after that novak had custom chips with novak part numbers, these are the last ones you can have good hope of repairing. getting into the mid 1990s and there are SMD resistors all over the place half ass soldered, like the construction of the esc got farmed out to china by that point and they were doing some bad hand assembly on the escs. there are globs of solder holding SMD diodes and resistors right on the solder points to the FETS making it REALLY hard to pull components for repairs.

now Tekin got a little a head earlier then novak the first gens after the delta autodrive already went double sided on the board and were through the hole components.
then tekin slowed down compared to novak. they stayed comparable into the first Microprocessor,, then Tekin went SMT and through the hole you can tell older components went into the tekin large chokes and adjustable pots where novak used newer smaller components and everything was SMT. Tekin would also File the part numbers off components to prevent people from getting the parts numbers and figuring out the specs the first 41X ESC are like a mess inside, half the old way half the new way, large microprocessor where the novak was TINY, looks like tekin did not make custom chips like novak did until much later on.

now the very first Novaks up to the T series is Tiny. the T-X esc got much larger, same with tekins they got larger with progressive generations.
high speed switching and all the options a microprocessor affords made them huge compared to first generation.

making the first gens larger was the inclusion of the LED circuit for detection of setup, they added some more fuse protection to the units as well, novak added Thermal protection as well which increased esc case size, i'm sure there is some more i'm forgetting which increased the case size. by the time the 410 is out they had 2 boards inside the case, main fet board and the daughter board with the microprocessor. and then of course going to one button setup.


with all the scans you have of the demons it wouldn't take much more work to schematic them and also make replicas :D

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Re: Demon 2C

Post by V12 » Wed Dec 21, 2016 2:23 pm

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/

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Re: Demon 2C

Post by bluewormx » Wed Dec 21, 2016 9:54 pm

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...

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Re: Demon 2C

Post by V12 » Wed Dec 21, 2016 11:01 pm

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.

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Re: Demon 2C

Post by bluewormx » Wed Dec 21, 2016 11:24 pm

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.

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Re: Demon 2C

Post by bluewormx » Tue Jan 10, 2017 4:39 pm

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
IMG_1478.JPG
IMG_1478.JPG (47.06 KiB) Viewed 346 times
Done is never done...
I re-applied the heatshrink in the other direction
seems like a better fit.

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