Mk1 Escort - voltage stabiliser
Discussion
One for the electrical experts:-
On a MK1 Escort I've replaced the dynamo with an Alternator
Does anyone know whether it's possible to remove the Voltage Stabiliser from the wiring loom without causing any problems.
I believe the Alternator has a voltage stabiliser as standard whereas the dynamo didn't and therefore needed it.
On a MK1 Escort I've replaced the dynamo with an Alternator
Does anyone know whether it's possible to remove the Voltage Stabiliser from the wiring loom without causing any problems.
I believe the Alternator has a voltage stabiliser as standard whereas the dynamo didn't and therefore needed it.
I personally would leave it in,because it will affect the accuracy of the readings the instruments give(particularly the fuel gauge!).This has been known to result in long walks for fuelfor some people! The voltage stabilisation refered to re the alternator is to regulate the charge voltage to the battery.
Dynamos used to have the old Lucas "control box " which was an electro-mechanical form of regulating the voltage.
Dynamos used to have the old Lucas "control box " which was an electro-mechanical form of regulating the voltage.
I binned the dynamo's voltage regulator awhile ago.
What voltage do the gauges work off?? I thought they would be 12V
If the alternator outputs 12V DC then surely the gauges should work OK?
I thought the Voltage stabiliser only had an effect because the Dynamo only worked above a certain engine RPM, whereaas the alternator works whatever the engine RPM is. So that's why I asked whetehr it was really needed in an alternator powered electrical system.
Do modern cars still have separate Voltage stabilisers?
thanks for your help
Mal
What voltage do the gauges work off?? I thought they would be 12V
If the alternator outputs 12V DC then surely the gauges should work OK?
I thought the Voltage stabiliser only had an effect because the Dynamo only worked above a certain engine RPM, whereaas the alternator works whatever the engine RPM is. So that's why I asked whetehr it was really needed in an alternator powered electrical system.
Do modern cars still have separate Voltage stabilisers?
thanks for your help
Mal
No, you need to keep the instrument voltage stabiliser. Irrespective of dynamo or alternator, the system voltage will vary according to load, state of battery charge and RPM, so instruments of these era were designed to work from a lower, stabilised, voltage (usually ~10v).
The mechanical stabilisers are very crude, they simply use a bimetallic strip and a heater to continuously switch the instrument feed on and off between 0v and the battery voltage. The average output voltage will be about 10v, and is reasonably independent of battery voltage. The gauges have a very slow response so only respond to the average voltage rather than the 0v-12v cycling.
It's possible to replace these old style stabilisers with modern integrated components if you wish, but as long as you use the original gauges and senders you will need some form of stabiliser.
The mechanical stabilisers are very crude, they simply use a bimetallic strip and a heater to continuously switch the instrument feed on and off between 0v and the battery voltage. The average output voltage will be about 10v, and is reasonably independent of battery voltage. The gauges have a very slow response so only respond to the average voltage rather than the 0v-12v cycling.
It's possible to replace these old style stabilisers with modern integrated components if you wish, but as long as you use the original gauges and senders you will need some form of stabiliser.
I have seen commercial ones, but I don't know where they came from. If you don't mind a bit of DIY you can make your own
Two points to watch.
First is what voltage is required. According to this page the Mk 1 Cortina changed from 10V to 5V in 1964. Could well be that the Escort uses 5V. In that case you need a 7805 in place of the 7810.
Second is that the 164club link is wrong about how to use the 7810 (the 7805 is the same). The capacitor value should be 100nF, not 10nF (0.1uF, not 0.01uF), and there should be two of them, not one - one from each outside leg of the regulator to the centre leg.
First is what voltage is required. According to this page the Mk 1 Cortina changed from 10V to 5V in 1964. Could well be that the Escort uses 5V. In that case you need a 7805 in place of the 7810.
Second is that the 164club link is wrong about how to use the 7810 (the 7805 is the same). The capacitor value should be 100nF, not 10nF (0.1uF, not 0.01uF), and there should be two of them, not one - one from each outside leg of the regulator to the centre leg.
Good point the input decoupling capacitor value is far too low to be effective, a 0.22uF or 0.33uF is typically recommended.
BTW, you don't necessarily need any capacitors on a 78xx regulator for stable operation; provided the supply impedance is low the input cap can be omitted, and the output cap is only there to help with transient performance on most manufacturers devices. It's certainly a good idea to provide them for the few pennies they cost though.
BTW, you don't necessarily need any capacitors on a 78xx regulator for stable operation; provided the supply impedance is low the input cap can be omitted, and the output cap is only there to help with transient performance on most manufacturers devices. It's certainly a good idea to provide them for the few pennies they cost though.
S47 said:
Mr2Mike
Make your own = A Good Idea - the link you provided was great, I'm surprised they ain't commercially produced though
Thanks for the help
Mal
As I say, I'm certain I have seen a commercial version, I just don't know who sells them. I can't imagine they are a big seller though, modern cars don't them as they either have moving iron gauges that have two windings to cancel out system voltage changes, or use stepper motors. The prehistoric bi-metallic regulators were fairly reliable however, the main reason you might want to change to a solid state version is to reduce radio interference which the originals were prone to.Make your own = A Good Idea - the link you provided was great, I'm surprised they ain't commercially produced though
Thanks for the help
Mal
Edited by Mr2Mike on Tuesday 15th June 23:56
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