Screwing in (clockwise) increases the speedo reading, screwing out (anti-clockwise) reduces it.
The tachometer can also be adjusted -- there is an obvious trimmer resistor on the circuit board.
Peter
Adjusting Jaeger speedometer
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Peter Cripps
Adjusting Jaeger speedometer
Perhaps everyone already knows this, but I discovered that it's quite easy to adjust the calibration on Jaeger speedometers. There is a screw on the back of the speedometer body:
Screwing in (clockwise) increases the speedo reading, screwing out (anti-clockwise) reduces it.
The tachometer can also be adjusted -- there is an obvious trimmer resistor on the circuit board.
Peter
Screwing in (clockwise) increases the speedo reading, screwing out (anti-clockwise) reduces it.
The tachometer can also be adjusted -- there is an obvious trimmer resistor on the circuit board.
Peter
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Neil
Re: Adjusting Jaeger speedometer
Peter,
Interesting, my Fulvia has Veglia instruments, do you know if such an adjustment is available with Veglia speedometers, I have never looked.
Neil
Interesting, my Fulvia has Veglia instruments, do you know if such an adjustment is available with Veglia speedometers, I have never looked.
Neil
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Huib
Electronic Veglia rev counter
Some months ago I made above schematic of the Veglia S2/3 rev counter electronics. As you can see there is a trimmer potentiometer.
The designer made the same error I made when I designed my first video monitor where the anode voltage for the tube is generated the same way the ignition in a car generates the spark voltage. The pulses are mean, particularly under fault conditions such as a failing condensor in the distributor, and require pulse load calculations for any resistors connected to the pulse. In the case of the rev counter, these calculations were clearly not made.
The 2k2 (2200 ohm) resistor R1 which is connected to the ignition coil, is a carbon film resistor of about 0,3 Watt. This is not enough. Many have failed and the others are baked brown.
Fortunately resistor technology has advanced quite a bit. You can now buy better rated resistors with the same mechanical dimensions or even smaller. The Philips types SFR25H, PR01 and PR02 are ok. I use PR02 (these are rated at 2 watts) simply because they are available at the local components shop.
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P. de R. Leclercq
Re: Electronic Veglia rev counter
Huib,
That is most interesting, and I am sure, very useful for Fulvia owners who have some electronics knowledge. (For seven years I was building valve hi-fi amplifiers!).
One question: you mention Veglia rev counters as fitted to S2/S3 Fulvias. The S2 instruments that I have seen are branded "Jaeger". Are they actually he same as the Veglia ones?
Incidentally on my first visit to a rolling road with a 1600 (in 1985) the operator was amazed at how accurate the rev counter was. He said is was just 50 rpm out at 6000. That of course is better than one per cent, not bad for 23-year-old Italian electonics!
Paul
That is most interesting, and I am sure, very useful for Fulvia owners who have some electronics knowledge. (For seven years I was building valve hi-fi amplifiers!).
One question: you mention Veglia rev counters as fitted to S2/S3 Fulvias. The S2 instruments that I have seen are branded "Jaeger". Are they actually he same as the Veglia ones?
Incidentally on my first visit to a rolling road with a 1600 (in 1985) the operator was amazed at how accurate the rev counter was. He said is was just 50 rpm out at 6000. That of course is better than one per cent, not bad for 23-year-old Italian electonics!
Paul
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Peter Cripps
Jaeger rev counter
Thanks for posting the schematic, Huib!
I believe the Jaeger tachometers are different from Veglia. The Veglia tachs have 3 connections, ground, ignition input, and 12V, while the Jaeger tach has only 2, ignition and ground.
I haven't traced the circuit of the Jaeger tach, but it appears to be extremely simple, just a few passive components. After cleaning and adjustment, mine seems reasonably accurate, amazingly so considering the crude circuit. (Actually, maybe it's not that crude -- after all, it seems to work, and it is nearly 40 years old!)
When I first checked the calibration, I found it was reading nearly 1000 rpm LOW. I wondered why I was having such difficulty revving to the redline .... !
Peter
I believe the Jaeger tachometers are different from Veglia. The Veglia tachs have 3 connections, ground, ignition input, and 12V, while the Jaeger tach has only 2, ignition and ground.
I haven't traced the circuit of the Jaeger tach, but it appears to be extremely simple, just a few passive components. After cleaning and adjustment, mine seems reasonably accurate, amazingly so considering the crude circuit. (Actually, maybe it's not that crude -- after all, it seems to work, and it is nearly 40 years old!)
When I first checked the calibration, I found it was reading nearly 1000 rpm LOW. I wondered why I was having such difficulty revving to the redline .... !
Peter
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Huib
Re: Electronic Veglia rev counter
Many of the S2 berlina's had Veglia instruments. I assume they have the same electronics. I have never opened one.
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Huib
Re: Jaeger rev counter
The tachometer was invented by Vitruvius in about 15 BC. A wheel dropped a pebble in a basket at every revolution.
Electronic rev counters work along the same principle. Instead of a pebble in a basket however a handful of electrons are dropped in a capacitor.
I haven't opened the Jaeger rev counter. I suppose it is possible to directly integrate the pulses from the ignition rather than reshaping it and use it to trigger a monostable multivibrator as in the Veglia unit. Apparently variables such as dwell angle, inductance of the coil, battery voltage, ignition condensor value and temperature do not influence the accuracy beyond an acceptable percentage. Interesting.
Electronic rev counters work along the same principle. Instead of a pebble in a basket however a handful of electrons are dropped in a capacitor.
I haven't opened the Jaeger rev counter. I suppose it is possible to directly integrate the pulses from the ignition rather than reshaping it and use it to trigger a monostable multivibrator as in the Veglia unit. Apparently variables such as dwell angle, inductance of the coil, battery voltage, ignition condensor value and temperature do not influence the accuracy beyond an acceptable percentage. Interesting.
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P. de R. Leclercq
Re: Electronic Veglia rev counter
Oh yes the S2 Berlines did have Veglia clocks - of course - but the coupés had instruments marked "Jaeger".
Paul
Paul
Re: Electronic Veglia rev counter
Huib Wrote:
-------------------------------------------------------
> >
> Some months ago I made above schematic of the
> Veglia S2/3 rev counter electronics. As you can
> see there is a trimmer potentiometer.
>
> The designer made the same error I made when I
> designed my first video monitor where the anode
> voltage for the tube is generated the same way the
> ignition in a car generates the spark voltage. The
> pulses are mean, particularly under fault
> conditions such as a failing condensor in the
> distributor, and require pulse load calculations
> for any resistors connected to the pulse. In the
> case of the rev counter, these calculations were
> clearly not made.
> The 2k2 (2200 ohm) resistor R1 which is connected
> to the ignition coil, is a carbon film resistor of
> about 0,3 Watt. This is not enough. Many have
> failed and the others are baked brown.
> Fortunately resistor technology has advanced quite
> a bit. You can now buy better rated resistors with
> the same mechanical dimensions or even smaller.
> The Philips types SFR25H, PR01 and PR02 are ok. I
> use PR02 (these are rated at 2 watts) simply
> because they are available at the local components
> shop.
Dear Huib
I have a 1972 Fulvia berlina and have fitted an old Sparkrite electronic ignition, running on the existing points. It runs well but I cannot get the Veglia tacho to run on the electronic setting. It runs on the conventional setting and I have tried all the different combinations of wiring suggested in the Sparkrite instructions. It seems that the 'trigger' impulse from the LT side of the coil is just not strong enough; with some wiring configurations, the tacho needle will struggle up to 1000 rpm reading with some revving but not respond properly. Any ideas?
A tach adapter? Some sort of diode booster? The Veglia tach has three connections: earth, live from ignition switch, and 'trigger' input from the LT (negative, points) side of the coil. It is not a 'loop' wire system.
-------------------------------------------------------
> >
> Some months ago I made above schematic of the
> Veglia S2/3 rev counter electronics. As you can
> see there is a trimmer potentiometer.
>
> The designer made the same error I made when I
> designed my first video monitor where the anode
> voltage for the tube is generated the same way the
> ignition in a car generates the spark voltage. The
> pulses are mean, particularly under fault
> conditions such as a failing condensor in the
> distributor, and require pulse load calculations
> for any resistors connected to the pulse. In the
> case of the rev counter, these calculations were
> clearly not made.
> The 2k2 (2200 ohm) resistor R1 which is connected
> to the ignition coil, is a carbon film resistor of
> about 0,3 Watt. This is not enough. Many have
> failed and the others are baked brown.
> Fortunately resistor technology has advanced quite
> a bit. You can now buy better rated resistors with
> the same mechanical dimensions or even smaller.
> The Philips types SFR25H, PR01 and PR02 are ok. I
> use PR02 (these are rated at 2 watts) simply
> because they are available at the local components
> shop.
Dear Huib
I have a 1972 Fulvia berlina and have fitted an old Sparkrite electronic ignition, running on the existing points. It runs well but I cannot get the Veglia tacho to run on the electronic setting. It runs on the conventional setting and I have tried all the different combinations of wiring suggested in the Sparkrite instructions. It seems that the 'trigger' impulse from the LT side of the coil is just not strong enough; with some wiring configurations, the tacho needle will struggle up to 1000 rpm reading with some revving but not respond properly. Any ideas?
A tach adapter? Some sort of diode booster? The Veglia tach has three connections: earth, live from ignition switch, and 'trigger' input from the LT (negative, points) side of the coil. It is not a 'loop' wire system.
Re: Electronic Veglia rev counter
Did you connect the wire for the rev counter to the wire coming from the points or to the - (minus) terminal of the coil?
I offer an electronic distributor on this site. See http://www.viva-lancia.com/specials/ignition/index.htm.
The rev counter works with it.
I offer an electronic distributor on this site. See http://www.viva-lancia.com/specials/ignition/index.htm.
The rev counter works with it.
