The Triumph Dolomite Club - Discussion Forum

If you give her all the bits & tell her what needs soldering to what & where...yes!

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Sprintless for the first time in 35+ years. ... Still Sprintless.

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1997 TVR Chimaera 450

That's the bit I'm trying to work out myself Can get them for about $350 from the States but that's a lot more incentive to blow myself (and the car???? ) up than the 15 quid for the voltage stabilisers on this thread

nice works stew, thanks for the "how-to"

spunkymonkey....have a search of your local electronic shops, here in Oz we have jaycar/Dick Smith/Radio Shack and a few others. This is one kit I found that could be altered...

http://www.dse.com.au/cgi-bin/dse.store ... View/K3234

this one takes 12V in and drives anything up to 24V out @2amps. $15AU. it would need tweaking to get 12V from 6V

or this one from "oatleyElectronics"

http://secure.oatleyelectronics.com//pr ... e38b69f5cd

which looks purpose built for your needs....

or this one which would need a tweak as well, but is capable of more power.....

http://secure.oatleyelectronics.com//pr ... e38b69f5cd

a step up transformer is a bit more work than a regulator, since transformers work on AC, not DC, but several kits now provide a cheap and easy solution. 6V to 12V is kinda' easy. There was a kit floating around that did 1.5V to 9V so you could replace expensive 9V "transistor" batteries with cheaper D cells.....just found it...

http://www.dse.com.au/cgi-bin/dse.store ... View/K3231

If you need the kits from Oz, give me a pm, but there should be equivalent kits in the UK

Out of interest, my students are busy making voltage regulators that give a steady, filtered output at any voltage from 1-12V from a kit. $5 each but 1.2Amps max. Stew's solution using the LM2940T is a lot quicker for the car.

Just to confirm, without the circuit diagram in front of me, the regulator is 12V and only services the gauges yeah ? so 1.2amps would be enough ?

stu

a bit of thread necromancy, but maybe this could be put into the faq section or "how to"

I recently made up a new voltage stabiliser for a friend in Hobart, whose stag was showing very high temperature readings.

here 'tis
the original unit, the male spade connection is the voltage going in, dark green. The female spade connector is the light green wire, stablised connection.
the components used, LM317T variable voltage regulator and two resistors used to set the voltage.
inside the old case. Apart from the rust, it works through a make break switch, which is similar to an old fashioned indicator flasher. The wire wrapped around the metal leaf heats it, which causes it to expand and break the contact, it then cools and comes back into contact. This happens many times a second (you can hear them when they are working, they vibrate). The duty cycle determines what voltage they give. There is an adjustable set screw on top of the case for fine tuning the output voltage.
more rust
new circuit.
The tab on top of the regulator is the output (as well as the middle leg) so it has been soldered directly onto the female spade connection inside the case. The right leg (Vin) has been likewise soldered to the male spade connector. The resistors go between Vout and Adj (left leg, 220 Ohms) and Adj and ground (1.5 KOhms), this gives a Vout according to:

Vout = 1.25(1 + R2/R1)

in practice the resistors have a tolerance and there is extra voltage due to the current drawn through R2, so a bit of trial and error is needed if you want perfection.
this is the battery voltage, note the red multi-meter probe on the battery positive terminal
This is the stabliser output, 9.94V is pretty damn close to the 10V needed, so I left it at that.

One extra connection though. The old stabliser had a pinch connection sandwiched between the top and the case which acted as a ground for the heating element. I figure this was hit and miss, so have drilled a small hole in the side of the case and run an earth lead, terminated in an eyelet, so when the unit is screwed down, you'll need to ensure this is earthed. When you clip the top on, just make sure the internal leads aren't shorting, plenty of room in the case so shouldn't be a problem.

I've also just made up 3 more stabilisers using another regulator chip, specifically designed for the job, an L2610,
http://www.datasheetcatalog.org/datashe ... 5f0zcy.pdf
one for my sprint, one for Thomas's sprint, one for the stag and I ran out of regs so left the best of the originals for the 1850 "donor"

so, there appear to be several ways to skin this cat,

stew's original LM2940T 10Volt Transistor
a variable regulator LM317T set up to deliver 10V (easily pushes through 1.5A)
a L7810 which is a fixed 10 volt reg, if you can find 'em
a L2610 which has 0.5A output and is another dedicated 10V reg

any of which will work fine and none require any extra filtering capacitors.

stu

The capacitors may or may not be needed- it all depends on things like distance from source (battery or generator) and what load is fed from the regulator. If something isn't right for the regulator, it may oscillate and output high frequency noise as well as 10V DC. Given the pence cost of a couple of capacitors, it isn't worth not fitting them. The values for any particular regulator will be in the manufacturer's datasheet or application note which can easily be found online (usually just typing the part number into Google will spit out several different manufacturers' and other sites with it). Also the input capacitor may give some protection from voltage spikes on the car supply (not exactly the cleanest of DC at the best of times).

It's also worth noting that some regulators- the 7810 for example, conveniently have the case metal tab as the ground terminal, so it can simply be screwed down to the car body or the metal box of the old regulator, but the 317 adjustable type has to have its tab insulated from ground since it's an active terminal (the adjustment voltage pin). This isn't difficult- ingenuity or a standard TO220 (the type no for the particular case format) insulating kit can be used.

The L2610 looks particularly interesting if you can find one, since it's actually specifically intended for automotive use and designed to cope with the car electrical supply. And it has a grounded tab too!

good observations

the filtering just isn't needed though, the gauges themselves don't respond fast enough, since they aren't designed to and nor do they need to. The old "bi-metal" reg would have cranked out a hella noisy level. Like 50Hz, zero to max voltage !

stu

Stu, you have a PM

Another common use for capacitors is for an AC to DC converter. Half or full wave rectification. Very simple really as you know an AC current follows a sin wave and a DC current is a flat line to convert an AC current to a DC current you can use a diode and a capacitor. When the wave is in the possitve part of the cycle it charges up the capacictor and when its in the negative it discharges. The diode will not allow the negative current to pass and thus a DC current is formed. Without the capactitor you will get regular pulses of current which is not usefull unless you are say timing something
This is half wave rectification and gives a varying DC current The bottom half of the diagram will dissapear as the diode cancels it out.

Full wave rectification uses 4 diodes and a capacitor to smooth the output giving a continues DC current.

Feed this into a voltage regulator and you get a nice smooth DC current which you could say run a radio off.
Full wave is more efficient but half wave is easier.

I know this is a bit off topic but if you built this circuit and conncected it to a voltage regulator you can do one of 2 things.
1. Run car electrics off of the mains to check they work before installing them
2. Build your own battery charger like I have and not pay through the roof, I brought the components of the school and built it cost about £10 and am still using it today 2 years later

A level electronics FTW

Now somebody please tell me why on earth I dont like wiring electrics in cars.
Paul

Be a good idea to transform down the mains to around 12V before rectifying, smoothing and regulating it, otherwise the poor regulator would have to stand off about 320V and dissipate 300+ watts for every amp out at 12V!

Filtering- granted the instruments won't care about HF noise- they don't noticeably resond to the pulsating (about 1-2Hz) output of the bimetal regulator (though if you peer closely at the fuel gauge, you may just see the needle "ticking" in time with the pulses)- but if the regulator is oscillating, its DC output tends to wander too since it's no longer being stably controlled.

Liking car electrics..... I think most people, myself included, don't like them much. Even though for our cars they're pretty simple in principle, in practice the combination of general inaccessibility, harsh operating conditions and components which really do display the art of design down to a cost can make them a pig to fault find and work on. In many cases, just a decent wiring diagram, with locations explicitly given for all in line connections and grounding points would make life a lot simpler. The bare bones circuit that is usually available can be little better than nothing!

I screwed a 7810 onto the bulkhead, with soldered flying leads attached with heatshrink on the 7810 terminals and spade connectors on the other end of the leads. It's nicely hidden next to the original regulator and works a treat, no resistors and no capacitors. It was in one of the club magazines.
Eventually the original regulator will be sent to the club and an upgraded one bought and fitted - but pennies are at a premium at the moment!

There's an article in the current edition (March 2010) of Practical Classics (page 86) on this very subject. The author is ex-Dolomite owner Frank Ashton who will be known to members who attend Yvonnne Birkin's meetings. The part in question is available from Maplin for 91p. It is part No. TS7810CZ/NC38CA and it can be ordered HERE

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Toledo Man

West Yorkshire Area Organiser
Meetings take place on the first Wednesday of the month at 8.00pm at The Old Brickworks, Wakefield Road, Drighlington, Bradford, BD11 1EA

2003 Volvo XC90 D5 SE (PX53 OVZ - The daily driver)
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1991 Toyota Celica GT (J481 ONB - a project car)
Former stable of SAY 414M (1974 Toledo), GRH 244D (1966 1300fwd), CDB 324L (1973 1500fwd), GGN 573J (1971 1500fwd), DCP 625S (1977 Dolomite 1300) & LCG 367N (1975 Dolomite Sprint), NYE 751L (1972 Dolomite 1850 auto) plus 5 Acclaims and that's just the Triumphs!

Check my blog at http://triumphtoledo.blogspot.com
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"There is only one way to avoid criticsm: Do nothing, say nothing and BE nothing." Aristotle

If you're still looking for someone to knock these up for the club, i'll quite happily do it. The only bit i'm not sure about is the zoinc plating, would tin be good enough?

This is one thing i will be doing on my car, when i rewire it

And btw, I love car electrics (at least on older cars )

Must be in the genes!

Are you related to the Prince of Darkness by any chance?

No I'm not - or at least as far as I know

But I do work in electronics - as an apprentice at the moment.

Just to give you an idea of what i can do - i'm working on designing a Multispark Capacitor discharge Ignition system for my car

Sounds like something off scooby doo that..