OverDrive Aftermarket "Logic Box"

[SpitFire6]

Hi,

 Tried the search with no joy.

I know this has been discussed before as I remember there was something in the courier.

My understanding is that it disengaged the OD when changing gear. It must be used with a momentary contact & will not work with the 2 position gear stick switch?
You depress the PushButton to engage or disengage the OverDrive?
There is more than one variant & they all work the same?

My questions are asked as it seems easy to make the standard gear-stick SPCO switch behave as a momentary contact in both positions. If anybody has already done this I will throw my Post-it Note in the bin.

Cheers,

Iain. 

 

 

[RogerH]

Hi Iain,

I make a version of the Logic box. It does all the things you want.

As for the switch. I use a press button on the end of a stalk that is near my right hand finger so changes are quick and easy.

The Moss switch for the 4A  This thing  is fairly easy to modify. Remove the spring loaded ball so the lever flops about and then bias it off with foam sponge etc. (or another spring)

Roger

[SpitFire6]

Hi Roger,

 Do you have a schematic for your one or are they for sale?
So, with the same button/switch; it is push to energise & push to de-energise OverDrive?

Cheers,

Iain.

[NonMember]

If you're expecting it to auto-disengage on change from 3rd to 4th, I think that will only work on the TR / big saloon / Stag. That gearbox has the inhibitor switch operated by the actual selector fork and thus switches off mid-shift. The small car box doesn't do that.

[rogerguzzi]

9 minutes ago, NonMember said:

If you're expecting it to auto-disengage on change from 3rd to 4th, I think that will only work on the TR / big saloon / Stag. That gearbox has the inhibitor switch operated by the actual selector fork and thus switches off mid-shift. The small car box doesn't do that.

Hello All

                I have a home made logic box but I have to reset the o/drive switch to re engage.

I modified my gearbox so it drops out between 3rd & 4th.

I also added a second switch so I could get o/drive on 2nd  as there is a big gap between 2nd & 3rd if you are loaded and climbing mountains passes

Roger 

ps here is how

http://sideways-technologies.co.uk/forums/index.php?/topic/8233-another-mad-idea/#comments

[SpitFire6]

48 minutes ago, NonMember said:

If you're expecting it to auto-disengage on change from 3rd to 4th, I think that will only work on the TR / big saloon / Stag. That gearbox has the inhibitor switch operated by the actual selector fork and thus switches off mid-shift. The small car box doesn't do that.

Hi NonMemeber,

 Ahh, that explains why I have not seen Spitfire mentioned. I assumed all OD gearbox lost the OD on gear change. ( I used to get a shock of my GT6 box. I thought it was the overdrive dropping out when I changed gear- Must have been when flicking the switch then. It was 30 years ago.).

I have a TR6 box with OD on top three gears. My input is the slide switch on the gear-stick. I like the switch. I can easily turn it into a flip-flop if the aftermarket modules are activated by momentary contact. I think. LOL.

 

Cheers,

Iain.

[SpitFire6]

3 hours ago, rogerguzzi said:

Hello All

                I have a home made logic box but I have to reset the o/drive switch to re engage.

I modified my gearbox so it drops out between 3rd & 4th.

I also added a second switch so I could get o/drive on 2nd  as there is a big gap between 2nd & 3rd if you are loaded and climbing mountains passes

Roger 

ps here is how

http://sideways-technologies.co.uk/forums/index.php?/topic/8233-another-mad-idea/#comments

Hi Roger,
Read the sideways post with interest. Seems I have read it before as I was the last post. I do remember the horse.

So your design requires re-engaging after shift. Don't they all? Do you use a single input or two?

Cheers,

Iain,

[RogerH]

Hi Folks,

my comment in the second post above was for the TR series of gearbox/Overdrive.

I have no knowledge of the other OD's and GB's.

 

Roger

[Clive]

Roger, all the small chassis cars with OD don't drop out of overdrive when changing between 3rd and 4th. That is about the only difference that matters in this case, and is an advantage I reckon.

[rogerguzzi]

Hello Ian

                What I mean is I have to reset the o/d switch ie off and on again.

What do you mean one input or two inputs?

Roger

[RogerH]

3 hours ago, clive said:

Roger, all the small chassis cars with OD don't drop out of overdrive when changing between 3rd and 4th. That is about the only difference that matters in this case, and is an advantage I reckon.

Thanks Clive,

The small chassis cars are a mystery to me.

 

Roger

 

[rlubikey]

Iain, it is possible to do a quite simple OD "Logic" box which uses the slide switch on the gear lever. The OD will stay engaged while you go between 3rd & 4th (as already noted) and only drop out if you visit 2nd or 1st (or reverse). When you go back into 3rd or 4th, the OD is inhibited and when you decide you want OD, I find that my thumb instantly recognises the switch is in the "engaged" position and it's second nature to slide "off" then "engage".

The circuit comprises two double-throw relays. I have two versions - the first is as published in the Courier decades ago - but I'm afraid I don't know the author. The second is based on the same idea, but modified by me so that the gear lever wiring doesn't carry live, so a short circuit won't blow the fuse - that's if you even have a fuse which I don't believe the standard wiring loom doesn't.

Cheers, Richard

[rlubikey]

Here you go, this is the original circuit from the Courier.

Let me know if you want my modified "short-circuit-proof" version.

Richard

[SpitFire6]

7 hours ago, rogerguzzi said:

Hello Ian

                What I mean is I have to reset the o/d switch ie off and on again.

What do you mean one input or two inputs?

Roger

Hi Roger,

 ahh, that is not the functionality I am after. I am trying to find the circuit that is triggered on & off via a push-button/ momentary contact or flick of a switch that enables & disables the OD.
By two inputs I meant a different type of activating switch.

Thanks,

Iain.

[SpitFire6]

2 hours ago, rlubikey said:

Here you go, this is the original circuit from the Courier.

Let me know if you want my modified "short-circuit-proof" version.

Richard

Hi Richard,

 Your description & circuit I have seen before but it's not the one I'm interested in. Somewhere.. It might be made by a TR company beginning with the letter R. around £ 90 & you need to modify the normal OD switch. It appears to disengage the OD on gear change & "push-Button" changes the state of OD every time it is pushed.

I made a little circuit to enable the normal overdrive switch to act as a pushbutton without modifying the switch.

Thanks,

Iain.

[SpitFire6]

Hi,

 This was the circuit.

But pointless unless the "logic Box" requires momentary contact. LOL.

Cheers,

Iain.

[SpitFire6]

Hi,

 here is mine.

8 wires.

Inhibit switches must be common ground like originals.

Selection switch is standard 3 terminal OEM type on the gearstick. Might add another input (9th wire) for momentary input. AKA pushbutton.

Output to an OD Lamp.
High current OP for solenoid with varistor to limit noise.
Input to dim external OD Lamp.
ATO fuse for the module (1 Amp)
ATO fuse for solenoid (15Amp)?
Ignition off resets the device to solenoid off for next time.
Changing gear drops solenoid off.

OD switch, engages or disengages OD in either direction. Circuit just looks for a change in switch position and acts.
 

Looks simple to make and no way near the cost of some I have seen.

Cheers,

Iain.

[SpitFire6]

Hi,

 I tried posting on the TR Forum but will not allow pictures so back here.
I gave up with relays when it's cheaper with a micro.

 Thought I would post my own logic box spec.

 My logic box has two outputs:

1. Volt free contacts to enable Solenoid.
2. Dimmable remote LED for Solenoid Status.

Nine Inputs:

1. PushButton or switch Input. (Edge Triggered).
2. Inhibit(s) input.
3. 6 Cylinder selection. (Connect to 12V).
4. 4 Cylinder selection. (Connect to 12V).
5. Clutch Input. Activated if 4 Cylinder selected. (Eliminates problem of inhibitor switches not dropping out while changing gear).
6. Sidelights Input. (Dims LED at night).
7. Wasted Spark selection. (Connect to 12V).
8. RPM input from the coil.
9. Internal or external setting of high RPM. (Trimmer or POT)

 

Works with any type of switch. Latching or momentary. If gearstick switch is used; A jumper needs fitting to the outer contacts.

OD drops out on gear change. 4 Cylinder boxes will need a clutch (Brake switch) fitted.

Will not be able to disengage Solenoid if RPM too high. If RPM is high & you change to 3^rd, the solenoid will not disengage and you will end up in OD 3^rd..

Dimmable external LED will mimic the state of the solenoid. The LED will flash if RPM is inhibiting disengagement.

High RPM trip point set after selecting the number of cylinders & if wasted spark.

 I looked at the relay ones and quickly realised that a £3 IC was a cheaper option.
It works fine on simulation and is about 15 lines of code. I NO I/O left but loads of space as the program takes up about 25% of space.
I don’t know if I need to interface to anything else?

Please comment before I waste too much time on this

 

Edited June 8, 2020 by SpitFire6
Added missing parts

[RogerH]

Hi Iain,

sorry - I missed your request late last week. see below a diagram of my circuit. It is designed for the TR series of GB's.

 

Regarding your pic  not being posted on the other forum.

Set the size to a maximum of say 100KB. It should post exactly the same as on here.

It may be possible to cut and paste - as I have done below.

 

Roger

[SpitFire6]

Hi Roger,

I can't find a suitable F to V circuit that does not include a chip or easy to program with the software I am using.

Problems with the circuit simulator. The programming software simulator has no problems. Never has. Cannot use it to count though, so have to use a voltage input for RPM.

The basic ladder is below:

The program will fit on a £1 8 pin chip. I sill have 2 analogue or digital pins left!
Yours works. Mine is still on the PC.

I was going to use a 555 for tacho interface & then found a micro with 6 I/O cheaper.
The thing that takes the longest time for me is the PCB layout. Wish I had sockets for ATO fuses & car relays. Hate having to make my own

So without speed input is relatively easy. I wanted RPM in for holding the OD in on Hi RPM or if you change down with OD on at hi revs. I want the function without additional parts. Would have given a shift light too.

 Glad I don't do this for a job> I will stick with PLC's. Which is what started this project for me. I have this program already but on a PLC.

 I like the "Bistable to replace 4000uf cap" Comment. The timer must have been cheaper.

Cheers,

Iain.

[RogerH]

Hi Iain,

I am a retired aerospace mechanical engineer/inspector. I have dabbled with electronics since the early 70's but never kept pace with technology.

It is now hard going and a very odd learning curve.  The resistor/Capacitor was sensible to me but I needed to get better (voltage independent) timing  - hence the 555

Your electronics is another world that I think I will never visit due to old age.

Good luck with your projects.

Roger

[NonMember]

24 minutes ago, RogerH said:

It is now hard going and a very odd learning curve.  The resistor/Capacitor was sensible to me but I needed to get better (voltage independent) timing  - hence the 555

There's a particular electronic project I maintain for a tech holiday for 12-15 year-olds, which uses a 555. It has caused us so much grief, with specs being marginally different between makes and new vs. old, that I really want to simplify the whole thing... by substituting one of those 8-pin, 6 I/O microcontrollers that Iain found cheaper. But that would replace not just the 555 but also the two 4000 series CMOS chips and most of the resistors, capacitors and diodes - the project would become too trivial as an electronics project and just a bit too awkward to run as a hybrid electronics / programming one.

[SpitFire6]

Hi,

 I use software breadboard so that I do not need to buy anything. I am too old to want to learn the 30 or so commands to program PIC chips so I use ladder programming software. Makes life very easy for me. I program Siemens PLC's before I was Furloughed.

Roger PM me if you are after some software. You can connect a 555 you can use the Software. 

Gone back to basics & started with a frequency to voltage converter for 12V and points/modern ignition. Need to set onboard jumpers to select:

4 Cylinder
6 Cylinder
4 with wasted spark & 6 with a wasted spark.
I have not picked resistors yet for the wasted spark modes.

7000 RPM I have set for 5V OP. I do not think more than this is needed for shift light & OverDrive Inhibit?
Setpoint for both will be set on second circuit.

So far it all works. On Sim.

Cheers,

Iain.

 

 

Edited June 10, 2020 by SpitFire6
Added