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Lucas Control Box - Solid State Replacement


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Guys, this isn't new, but I just learned of this solid state replacement for the old electromechanical control boxes.

 

I really don't have any further details regarding performance, etc. However, if it works well it could be a godsend for anyone having problems adjusting the old "BOX", and at $80 , it's not so dear!

 

sold state voltage regulator

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This is definitely one for me Frank and I will be trying it out soon. I have just found a company in Warwickshire who will refurbish my old ones and the first unit just arrived in the post together with my dynamo also rebuilt. The control box is so clean and new looking that it is in better shape than the new ones available from the usual suppliers. I hope to fit both units tomorrow morning if it is not raining.

Thank you for the link and I will post results later on.

 

Yours hopefully, Richard

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I wondered how long it would take for someone to come up with a good alternative using solid state technology. Now all we need is someone doing it over here, as with the exchange rate being what it is at the moment US imports are now a bit dear with carriage as well.

Stuart.

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I don't have an opinion about the New Hampshire firm mentioned in the link, and perhaps they do quite good work, but it's worth noting that one doesn't have to go to a specialist for a solid-state voltage regulator.

 

If you're reasonably handy with a soldering iron, and not afraid of a little Web research, I think it would not be too difficult to assemble one of these yourself. There's nothing mysterious about the technology, and all of the components are cheap and readily available. I don't have any circuit diagrams or links handy, but a quick Google search turns up a lot of potentially useful leads (no pun intended).

 

Please note that I am not suggesting that the right thing to do is to run out and acquire a quantity of circuit boards and an electrical engineering degree; I'm just saying that if you are concerned about the cost of the components and/or are on the wrong side of the current exchange rate, you have an alternative to consider. You may do a little reading and find that it is much simpler than you thought. Maybe think of it as a fun project for a rainy afternoon. :lol:

 

All of which reminds me of a question I have been meaning to ask: is there a reason to fork over for Lucas-branded overdrive relays for Laycock A-type-equipped cars? As noted elsewhere in the forum (for example here), the Lucas relay is simply a logic circuit like any other relay. Are we just paying for the correct appearance? I'm not being snarky here, just trying to confirm for myself that I don't have to spend $45 on the overdrive relay if I don't want to.

 

Regards,

Vittorio

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I don't have an opinion about the New Hampshire firm mentioned in the link, and perhaps they do quite good work, but it's worth noting that one doesn't have to go to a specialist for a solid-state voltage regulator.

 

If you're reasonably handy with a soldering iron, and not afraid of a little Web research, I think it would not be too difficult to assemble one of these yourself. There's nothing mysterious about the technology, and all of the components are cheap and readily available. I don't have any circuit diagrams or links handy, but a quick Google search turns up a lot of potentially useful leads (no pun intended).

 

Please note that I am not suggesting that the right thing to do is to run out and acquire a quantity of circuit boards and an electrical engineering degree; I'm just saying that if you are concerned about the cost of the components and/or are on the wrong side of the current exchange rate, you have an alternative to consider. You may do a little reading and find that it is much simpler than you thought. Maybe think of it as a fun project for a rainy afternoon. :lol:

 

All of which reminds me of a question I have been meaning to ask: is there a reason to fork over for Lucas-branded overdrive relays for Laycock A-type-equipped cars? As noted elsewhere in the forum (for example here), the Lucas relay is simply a logic circuit like any other relay. Are we just paying for the correct appearance? I'm not being snarky here, just trying to confirm for myself that I don't have to spend $45 on the overdrive relay if I don't want to.

 

Regards,

Vittorio

The Lucas 6RA overdrive relay was used for a lot of cars through the fifties and sixties and they are pretty long lasting. Also they can be opened up and the contacts cleaned and then they will go on again for many years. I buy them up when I see them at autojumbles as they are quite often cheap and use them for Kenlowes etc as piggy backed above the overdrive one they do look as if they should be there. The newer relays dont seem to last the course as well and dont look very "Period" either. (No doubt Tony Thompson will tell me otherwise ;) )

Stuart.

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I

If you're reasonably handy with a soldering iron, and not afraid of a little Web research, I think it would not be too difficult to assemble one of these yourself. There's nothing mysterious about the technology, and all of the components are cheap and readily available. I don't have any circuit diagrams or links handy, but a quick Google search turns up a lot of potentially useful leads (no pun intended).

 

Vittorio: Sounds like you know what you're doing. I for one will be looking forward to your electronic schematic diagram, list of parts and assembly instructions. :)

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Surely, the logical replacement for the Lucas control unit is a change to negative earth and replacement of the dynamo with an alternator. That way, the control box becomes completely redundant and one gains the benefit of more amps at low revs.

In the not-so-long-run, this is a cheaper and more reliable option.

I know it's not original and it won't do you much good in the concours competition, but it's simple and effective!

Ian Cornish

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Hello,

one should be aware that making electronic circuits working in the range of 5° to 25°C is not difficult, but having the same circuit working reliably from -10° to 50°C is far more critical and so a good shematic with the best quality of components are necessary.

Guy

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Hi Stuart,

 

Not on this one. I absolutely agree with your logic re pulling them apart and cleaning the contacts. Modern relays are not so easy to trouble shoot, and while a solid state relay (e.g. a big MOSFET) would do the job forever, these cannot handle big reverse voltage spikes so must have suppressor diodes around them.

 

The concern I have is that although the logic for the control circuit is pretty simple, I don't understand why anyone would you use modern electronics to solve a problem related to having a dynamo when using an alternator solves the problem more effectively!

 

Regards

 

TT

 

 

The Lucas 6RA overdrive relay was used for a lot of cars through the fifties and sixties and they are pretty long lasting. Also they can be opened up and the contacts cleaned and then they will go on again for many years. I buy them up when I see them at autojumbles as they are quite often cheap and use them for Kenlowes etc as piggy backed above the overdrive one they do look as if they should be there. The newer relays dont seem to last the course as well and dont look very "Period" either. (No doubt Tony Thompson will tell me otherwise ;) )

Stuart.

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Hi Guy,

 

Modern electronic components are generally fine for the range of temperatures you state, but the values of resistors etc would need to be stable at these temperature ranges, which is not so easy. Mil-spec devices would suit, but tend to be two or three times more costly. Though component costs are piddling compared to the manufacturing costs of any circuit when manufacturing in bulk.

 

TT

 

Hello,

one should be aware that making electronic circuits working in the range of 5° to 25°C is not difficult, but having the same circuit working reliably from -10° to 50°C is far more critical and so a good shematic with the best quality of components are necessary.

Guy

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Not on this one. I absolutely agree with your logic re pulling them apart and cleaning the contacts. Modern relays are not so easy to trouble shoot, and while a solid state relay (e.g. a big MOSFET) would do the job forever, these cannot handle big reverse voltage spikes so must have suppressor diodes around them.

 

The concern I have is that although the logic for the control circuit is pretty simple, I don't understand why anyone would you use modern electronics to solve a problem related to having a dynamo when using an alternator solves the problem more effectively!

 

Good point about the Lucas o-drive relays. My question answered.

 

I quite agree about the generator/alternator thing-- which is why I won't be posting any circuit diagrams and parts lists for DIY voltage regulators. ;)

 

-10C to 50C? In a Triumph? Guy, you are TOUGH! :D

 

Regards, Vittorio

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Surely, the logical replacement for the Lucas control unit is a change to negative earth and replacement of the dynamo with an alternator. That way, the control box becomes completely redundant and one gains the benefit of more amps at low revs.

In the not-so-long-run, this is a cheaper and more reliable option.

I know it's not original and it won't do you much good in the concours competition, but it's simple and effective!

Ian Cornish

 

Ian: I understand your argument but perhaps the appeal is that one retains the original "look" and with added reliability.

 

fja

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Hi Frank,

 

retaining the original 'look' is all well and good, but when it comes to replacing an electro-mechanical voltage regulator with a bunch of electronics inside the original box . . . . as opposed to switching to an alternator system ?

 

It all seems a bit like reinventing the wheel, at least to me.

 

It's not as if traditional voltage regulators were an endless source of problem. Either they worked, or they needed fixing, but they weren't like a regular service item.

 

Cheers,

 

Alec

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The voltage regulator in my 1958 TR3A is the same one that came with the car when I bought it 51 years ago. About 5 years ago, I felt I needed to carry a spare with me so I bought a new Lucas unit and without installing it, I removed my original one and compared resistance and voltage values for the new one vs the original one. The new one had all different readings. I put the new one into the TR as a test and it wouldn't work. So I put the original one back in and it's just fine. See the photo. I feel that this new solid-state unit might be what I'm looking for as a spare - just in case.

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If originality really is important to you, but you were prepared to swap to negative earth (a small but almost unnoticeable change), you could purchase one of those alternators which looks (from the outside) like a dynamo. Then, you get hold of a duff voltage regulator, rip out its innards, and use it as a connector block by doing the necessary linking beneath the cover. I believe that these alternators which look like dynamos are more expensive than a conventional alternator, but those I have seen certainly look like a dynamo.

Ian Cornish

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If ... you were prepared to swap to negative earth (a small but almost unnoticeable change)...

Just a note of caution. I have read that there are positive and negative earth versions of the voltage stabiliser used in TR4As. Lynda's early TR4A is still positive earth, so if I were to convert it to negative earth I assume I would also need to change the stabiliser?

 

[Currently (no pun intended) I have no driving need to do so, as my TR3A is also positive earth and I don't want to confuse my tired brain when swapping between cars :unsure: ]

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Since the "voltage regulator" is an electro-mechanical device of the utmost crudity, I cannot see any reason for it to care which way the current is flowing! It operates much as the trafficator flasher unit - a bimetallic strip is heated (indirectly in this case) by the current flow until it bends and so breaks the circuit. Then it cools, the circuit is re-established and the process is repeated. The result is an output which is either battery voltage or zero, but which averages - over a period of time - about ten volts. Since both the gauges for temperature and tank level work on the hot-wire principle and therefore are quite sluggish (unlike the gauges on the TR2/3/3A), this simple arrangement is good enough.

It may be that Lucas/Triumph changed the external appearance of the stabiliser over the period of TR4/4A production, but - as explained - there should be no polarity issues.

Ian Cornish

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  • 1 year later...

Hello,

Some information on electronic replacements for the lucas RB106 is now available now on

www.worldphaco.net along with some interesting information on Laycock overdrive units & other topics.

The 3rd regulator unit relating to this RB106 project will have its final photos put up this weekend, the circuitry is already there showing how you can incorporate an alternator regulator into the design as one option.

I'm hoping that these projects will inspire someone to manufacture a rugged commercial unit for TR owners.

Hugo.

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Since the "voltage regulator" is an electro-mechanical device of the utmost crudity, I cannot see any reason for it to care which way the current is flowing! It operates much as the trafficator flasher unit - a bimetallic strip is heated (indirectly in this case) by the current flow until it bends and so breaks the circuit. Then it cools, the circuit is re-established and the process is repeated. The result is an output which is either battery voltage or zero, but which averages - over a period of time - about ten volts. Since both the gauges for temperature and tank level work on the hot-wire principle and therefore are quite sluggish (unlike the gauges on the TR2/3/3A), this simple arrangement is good enough.

It may be that Lucas/Triumph changed the external appearance of the stabiliser over the period of TR4/4A production, but - as explained - there should be no polarity issues.

Ian Cornish

 

 

 

 

They did change the terminal type on the volt stabs between TR4/4A and TR250/5/6.

From 2 males to a male and a female. It always threw me when the factory supersceded a part number to something that really was not a direct fitment, but clearly did exactly the same job. I guessed it was to do with the relocation of the unit from the footwell panel to the back of the speedo instrument - Easier to see where the wires went in the footwell when connecting the loom? Or was it a way of 'error proofing' the assembly procedure of the (even) later cars. The term 'fool proof' having been outlawed by the unions, as clearly The Standard Triumph Motor Company would not employ fools to build their cars......

 

Cheers

Peter W

Edited by BlueTR3A-5EKT
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