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Over Drive Logic revisited


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5 hours ago, DRD said:

That's probably the one that was made by Tim Walker a former TRR member, sadly no longer with us now. Works really well.

It probably was. I found the email transaction this morning and I think it was someone called Walker selling it. 

Rgds Ian

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Without dismissing either Roger's or RobH's designs, which are both excellent options, it is possible to use a much simpler mechanism to improve the operation of the overdrive.

Mine uses the standard Overdrive relay, with two diodes attached. (Total cost less than £1.00). The momentary switch and 12 Volt LED are optional. The standard Overdrive switch can be used by switching on then off. I have used 1N4007 Diodes, but other diodes could be used. (NB I have close to 1000 1N4007 diodes that I bought about 10 years ago, if anyone needs a couple.)

I like Roger's use of a  momentary switch stalk extension.  It gives me ideas for doing something similar.

PS - Although my design does not use PCBs, the normal etchant used for PCBs is Ferric Chloride. Painting the PCB using Humbrol enamel to protect the required copper connections works well, and the etchant works OK at room temp, but works far quicker if heated. (note - not too hot - it shouldn't boil). It washes off with water. The enamel can be removed using wire wool, which also prepares the copper for soldering.

 

989032177_OnerelayODcontroller.thumb.png.f48f25ecc2b07e92404cb644b0ef05e9.png

TT

 

Edited by tthomson
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Hi Tony,

I'm all for simplicity. 

What holds your relay in once the momentary switch is open circuit.

 

I tried to improve my stalk by putting the LED on the button and putting the switch at the bottom of the stalk.

This was not a good idea.     How do you operate the switch when there is a 6" airgap between it and the button.

I used a bicycle Bowden cable. This works well on the bench but is awful fitted to the car. Too much TRavel.

Back to the drawing board.

Roger

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1 hour ago, tthomson said:

Without dismissing either Roger's or RobH's designs, which are both excellent options, it is possible to use a much simpler mechanism to improve the operation of the overdrive.

Mine uses the standard Overdrive relay, with two diodes attached. (Total cost less than £1.00). The momentary switch and 12 Volt LED are optional. The standard Overdrive switch can be used by switching on then off. I have used 1N4007 Diodes, but other diodes could be used. (NB I have close to 1000 1N4007 diodes that I bought about 10 years ago, if anyone needs a couple.)

I like Roger's use of a  momentary switch stalk extension.  It gives me ideas for doing something similar.

PS - Although my design does not use PCBs, the normal etchant used for PCBs is Ferric Chloride. Painting the PCB using Humbrol enamel to protect the required copper connections works well, and the etchant works OK at room temp, but works far quicker if heated. (note - not too hot - it shouldn't boil). It washes off with water. The enamel can be removed using wire wool, which also prepares the copper for soldering.

 

989032177_OnerelayODcontroller.thumb.png.f48f25ecc2b07e92404cb644b0ef05e9.png

TT

 

That is a delightful circuit for its simplicity.

All I now Ned to do is devise a method the convert an original TR3A egg shaped switch to spring loaded passing contact operation.

Thank you

Peter W

 

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1 hour ago, RogerH said:

Hi Tony,

I'm all for simplicity. 

What holds your relay in once the momentary switch is open circuit.

Roger

The top diode feeds 12V back from C2 to W1, but as far as I can see to take it out of O/D you would need to move the gear lever to neutral.

Bob.

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Yes. TT's circuit provides the logic function of disconnecting OD with an up or down-shift but doesn't allow you to switch the OD off manually. (That is why I added the complication a second relay to give that function in my effort above.) 

In this circuit you could do that with a separate push-to-break switch either in the brown lead or else in series with the top diode. 

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I'll join the party if I may with a design I put on the forum in 2017

It uses a push switch on the dash or gear knob to engage the OD and another push switch operated by the clutch pedal to disengage it.

The clutch pedal switch is fitted in the same way as a switch used to operate the brake lights from the pedal.

A quick blip of the clutch pedal disengages the OD if needed. (You adjust the switch so the slightest depression of the pedal operates it.)

(Thanks go to Bob who helped modify my origional design to make it simpler.)

OD.jpg.24b008480d85799ad950adc312cd414a.jpg

Charlie

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9 minutes ago, Charlie D said:

 

I'll join the party if I may with a design I put on the forum in 2017

It uses a push switch on the dash or gear knob to engage the OD and another push switch operated by the clutch pedal to disengage it.

The clutch pedal switch is fitted in the same way as a switch used to operate the brake lights from the pedal.

A quick blip of the clutch pedal disengages the OD if needed. (You adjust the switch so the slightest depression of the pedal operates it.)

(Thanks go to Bob who helped modify my origional design to make it simpler.)

OD.jpg.24b008480d85799ad950adc312cd414a.jpg

Charlie

But you dont need to use the clutch to engage or disengage overdrive.

Stuart.

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5 minutes ago, stuart said:

But you dont need to use the clutch to engage or disengage overdrive.

Stuart,

No, but it allows you to drop out of the OD when ever you change gear (up or down) without doing anything else other than de-clutch, which is what you would do anyway.

If you want to drop out of OD without changing gear you just need the slightest touch on the clutch pedal. (No need to press it right down.)

I used the idea for several years on a Rover 90 I had it and it seemed like a lazy way of doing things (Being a lazy sort of person I quite liked it.)

Charlie.

 

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2 hours ago, Lebro said:

The top diode feeds 12V back from C2 to W1, but as far as I can see to take it out of O/D you would need to move the gear lever to neutral.

Bob.

Hi Bob,

Yes you are correct about shifting gear to disengage the overdrive, but cost of the solution was minimal! Shifting to Neutral and back will also disengage it.

I have also toyed with adding another switch to actively disengage the overdrive. ideally the switch would be in series with the gearbox switches (where the original overdrive switch was located!).

I have considered adding a momentary switch to the top of the gear lever, and using the existing overdrive switch to disengage, but I'll live with it for the time being. (Too many other things I need to do)

TT

 

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I know I am biased and have been using Revington's Logic Overdrive since I installed it in 2004, but it strikes me that any system which requires the driver to move the switch from OFF to ON and back again cannot truly be described as a Logic system.

With all due respect to those who have posted their various designs here, I believe that a Logic Overdrive should require solely the flick of a lever to operate in either direction, or change of gear (movement of the gear lever through neutral) to change to OFF.

Perhaps one of our Forum members can design a system which requires just a vocal command from the driver: "Alexa, engage overdrive".  I'll get my coat!

Ian Cornish

Edited by ianc
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In the sixties they promised us flying cars by the Year 2000, like the Jetsons. But here we are, still can't even decide the best way to move some cogs around. As a generation, we've been betrayed.

But I am enjoying this thread. The clutch pedal to disengage OD is an intriguing idea, as coming down through the box into (say) a roundabout typically involves 4OD -> 4 -> 3 etc  and the clutch pedal would achieve at least that first shift without any hands off wheel. Neat.

Nigel

Edited by Bleednipple
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42 minutes ago, ianc said:

I know I am biased and have been using Revington's Logic Overdrive since I installed it in 2004, but it strikes me that any system which requires the driver to move the switch from OFF to ON and back again cannot truly be described as a Logic system.

With all due respect to those who have posted their various designs here, I believe that a Logic Overdrive should require solely the flick of a lever (or the press of a button)to operate in either direction, or change of gear (movement of the gear lever through neutral) to change to OFF.

Perhaps one of our Forum members can design a system which requires just a vocal command from the driver: "Alexa, engage overdrive".  I'll get my coat!

Ian Cornish

I'm not sure if there is any true logic to any of these boxes.

They have a certain convenience and some more than others.

The Revington box and my one have the simplest controls - momentary switch or press button to engage (or disengage if you wish).

However all the boxes described above have a level of convenience that suits the owner. It takes you out of gear at a point that you want.

I like my complicated system - because I prefer to make/design it rather than just use it.  In the early 80's I made a train set lay out for my son.

It wasn't long before the soldering iron came out and I had a multi engine lay out controlled by IR.

Roger

 

Edited by RogerH
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30 minutes ago, ianc said:

With all due respect to those who have posted their various designs here, I believe that a Logic Overdrive should require solely the flick of a lever to operate in either direction, or change of gear (movement of the gear lever through neutral) to change to OFF.

Which is exactly what mine does Ian, but it does require a non-standard lever switch. 

Edited by RobH
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Hi Folks,

I have just solved an oddity on my OD Logic box indicator LED

Since last year some time the LED would stop working. and then a few days later it would work.

I checked out the circuit, and the LED, and could not find a cause.

This happened again yesterday after fitting the my latest creation (update). I checked and cleaned all the tracks on the PCB but they were clean to start with.

Also the PCB arrangement for the LED is very simple - 12V through a Normally Closed relay contact, then through a 1K resistor and to the LED via a connector.

I checked the LED insitu running 2V through it and it worked a TReat. But it would not work through the Logic Box.

Put the whole lot on the bench. 2V from my bench PSU and the LED worked with a 10mA current draw

Put 12V through it via a 1K resistor and it doesn;t work - yet it still draws 10mA. 

So the LED still draws current but no longer glows - unless powered with 2v - very very odd

 

Fitted a new LED to the car and it works perfectly.

Roger

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Originally, I designed a logic driven O/D controller, built it, and it worked, It was complex circuit when compared to a relay, and I like to reduce designs to the bare minimum where I can. Hence the two diode option. However, I will see if I can find the logic circuit and post it here.

TT

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You should never apply voltage (even just 2V) directly to an LED without a current limiting resistor. It could easily draw too much current, & damage it's self.

Bob

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609947020_ODlogicbox.thumb.jpg.72dffb80475d3d61fdfe73e849e3faae.jpg

In the picture is the test version. Original is mounted in a box like below and mounted in the car besides the fuse box.

 

Interesting to see how others approach to the problem.

I kept the original switch for OD and added this item consisting of two relais, a resistor and a cap.

Unable to make da drawing I can say this item allows OD engage in 3rd and 4th if OD switch is of and than on is pulled.

After gear change between 3 and 4 the OD is kept active for 6 seconds.

If OD switch is forgotten in "ON" it will not engage when 3rd or 4th is engaged again. Than it must be switched of and on again.

Unfortunately the four parts, the housing underneath and the plate to solder it on was more than 10GBP.

It is about 25GBP.

 

Edited by TriumphV8
Mistakes
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5 hours ago, ianc said:

Perhaps one of our Forum members can design a system which requires just a vocal command from the driver:

Voice activated Overdrive?

No problem.

Here’s a good place to start.

 

https://www.instructables.com/Voice-Activated-Relay-Switch-Arduino/

 

If you Google “Arduino voice activated switch” you can find loads of examples of different ways to do it.

 

Come on Roger.

Get your soldering iron out.

(Actually… you don’t even need a soldering iron.)

 

Charlie.

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I’m impressed by the high flying electronic discussion here, which is way beyond my understanding. I find my original pear shaped OD switch perfectly adequate for my needs. What’s more, I can wire it up, test it and even repair it if I have to - like the rest of the (simple) car.

I don’t wish to be nasty but this thread reminds me of the beginnings of Excel and even Multiplan when folks would turn up to management meetings 30 years ago with impressive sheets of legthy tables until one day the boss made the remark “Intellectually it’s interesting, but is it useful?”

I’ll get me coat

james

 

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Hello James,

"Is it useful?"

Quite possibly not.

I've spent my life designing useless things.

Working out how to do things. Thinking up different ways to do things.

Maybe totally useless things.

But having FUN while I do it.

To me, that's what it is all about.

Charlie.

 

Edited by Charlie D
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Despite being in electronic design for 40 + years I feel no burning desire to move away from the original overdrive switch setup.

(But if I did it would be really complicated :))

Bob.

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2 hours ago, Lebro said:

Despite being in electronic design for 40 + years I feel no burning desire to move away from the original overdrive switch setup.

(But if I did it would be really complicated :))

Bob.

Hi Bob,

I think that is the fascination. I had an aerospace engine/airframe apprenticeship- anything mechanical was understood and sorted.

Then spent 36 years looking for cracks etc - what I don;t know about crack inspection could be written on many A0 pages (double sided) 

However part way through my apprenticeship (about 1968) I became part of a blues band and became interested in noise boxes that hadn't been invented yet.

Great fun to build but did they work - basically no. As for the WW electric piano.

Whatever your trade you will always be interested in the opposite - Ying & Yang 

Roger

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