Push Button Shift Box

cd4028 schematic

I'm trying to build a push button shift box. In order to shift a gear, +12v has to be applied to two wires either one on, both on, both off or the other on. I would like to be able to make this work with push buttons. I was thinking i'd need to use relays to supply the power to the wires, but the problem I ran into is... How would I turn the 1st (1st gear circut) off, when I push the button to shift to 2nd gear? I would like to get away from the 3 position switch as it is WAY to easy to kick the car into a low gear by accident. My goal is to make a 4 button box to switch to the 4 gears.


3 position switch
TOP ON --- DPDT Relay --- yellow/orange +12 1st
Middle OFF --- yellow/orange off. 3nd
Bottom ON --- yellow +12 2rd


Toggle ON --- Orange +12

Hello KrazyTurboTsi,

I think you could do that using relay logic. If you know how to make a self-retentive relay circuit, this seems a typical application. Just remember to put Normally open closed of every relay in series with the retention branch. That way when you push a button for a new shift the corresponding realy closes, and opens any previously active circuit.
Hope this helps.
Best regards!

You actully kinda lost me there. So your saying, put the switch wire for the previous gear thorugh the NC circut of the next relay? so when I energize the circut it cuts the previous... Although, I need to be able to upshift, and downshift using these buttons, I.e button 3, press button 4, then down to 3-2-1

Added after 11 minutes:

I need to be able to go 1-2-3-4, then 4-3-2-1, or in any order in between 1-2-1-2-3-2 etc etc. and have it ALWAYS shut off the previous circut. With what you just said I think I could build that, if it was only 1-2-3-4. Im not positive how I would go back down. If you or someone can explain in text, how to wire that, I could build it no problem. I'll elaborate on the circut real quick, with hopes of help (i've gotta hit the speedway tommorow) with hopes of using this new shift box...

well... on a car, the transmission shift solenoids are controlled by two +12v wires. By applying +12 to the wires, either both on, wire a on, wire b on, or both off, it shifts the 4 different gears. I want to be able to shift he gears with push buttons. Obviously I need only 1 circut on at a time, that's where im stuck. Switching the previous circut off when I turn on the next, i.e shifting from 1st to 2nd, 1st gear circut needs to shut off when I touch the button, same with downshifting. Currently I have a 3 position switch, and a regular toggle to shift the gears. The 3 postion controlls 1-2-3 and the toggle controlls OD. 1st gear is on a relay because it uses +12 to both A&B to shift, and could cause obvious problems it if wasnt seperated from the rest. Consideration must be taken that both wires will never be energised at the same time, besides when need them to be (1st gear) or the car will shift into 1st. I found that out the hard way before. It so happens 1st gear is both wires +12v. With my current toggle setup, I almost took out another car while testing. I had OD on +12v to orange wire, and slowed down, without thinking I tryed to downshift into 2nd which is +12v yellow... threw the car into 1st gear at 50... it was ugly haha. Here's a another quick rundown of what wires need to be energised to cause the shift, if anyone wants to make a schematic or even text schematic...

1st gear, 12+v orange and yellow
2nd +12v yellow
3rd both yellow and orange off
4th +12v orange

To realize your project you need something like left/right shift register, for example 74HC194 ( **broken link removed** ) ..
Have a look at the attached circuit .. it is only conceptual diagram and some other details have to be added to make it working ..
Other option would be to employ a small microcontroller and replace shift register and all associated ICs and connect 2 push-buttons to its External Interrupt pins ..
Regards,
IanP

Hello again,
Lest's consider the 2nd shift as example.
You close the 2nd shift relay by a push button in parallel with a series of:
.- N.O. contact of 2nd shith relay.
.- N.C. contact of 1st shift relay
.- N.C. contact of 3rd shift relay
.- N.C. contact of 4th shift relay

Assume that 2nd shift is engaged. Now you push, let´s say the 4th shift push button. 4th shift relay engages, it´s N.C. contact opens the self retaining branch in 2nd shift relay (in all others relays, in fact) and 2nd shift relay disengages.

Best regards

Ok you lost me, and I still dont see how I can go backwards, and I still need to supply power to at least 1 +12v wire, because I use a relay for 1st anway. 3rd gear, uses no wires to shift, so no wires need to be energised to shift to that gear. If you could type out something like I did above, that would be awesome. Here's the shift wires again. I also need to be able to go 1st 2nd then maybe 3rd back down to 2nd, etc etc. Sorry for the slew of questions, but your responses are still a bit above my level.

1st gear, 12+v orange and yellow
2nd +12v yellow
3rd both yellow and orange off
4th +12v orange

Added after 10 minutes:

btw, I need to do this with as few parts as possible. I dont want to have to have tons of things because the more parts involved the more problems and space it will take up.

Attached is a diagram, if you could please maybe show the wireing on that, it would be awesome.

Hello,

Here is a quick and dirty, (very quick and really dirty!) circuit. Take a look and tell me if if works for you.

Best regards

edited

Me and my buddies ran into a new problem, even if we do get the relays to energize and cut off the proper circuts automaticly, when I try to downshift, the button will still be mechanicly in the on position (down). The circut must remain on the entire time im in the gear. So i'd need a pushbutton that stays on. I was wondering if this can be doen with a chip of some form, one that when I press button A it energises wire A & B. Then when I press button 2, it turns off circut 1 (A&B) then energises circut 2 (wire b) so on and so forth, and also does the same backwards, when I go from circut 4 to circut 3, it shuts off circut 4.

Well, you will be having new problems all the time ..
However, this is the reason I tried to introduce some electronics to solve the puzzle ..
If I were you I would employ a small microcontroller ..
I know it is not "asap" solution but having this implemented you can always modify software and --> hardware remains the same ..
So, consult with your "buddies" and seriously consider this option ..
Regards,
IanP

None of us really even know anything about anything chip based.

Added after 22 minutes:

IanP, I just looked over the shiftbox you attached, it looks like it's exatly what I needed. From what I see it's a 2 button shift box capable of upshifting and dowshifting. Does it supply voltage the entire time it's in a gear? or only when the button is pressed? You said componets need to be added to make it work, can you tell me what ones, or maybe supply them in another schematic?. Maybe if any of you have a electronics circut builder, can make it there, then supply the shcmeatics, that would be great. I've got circut maker 6 but it will not allow me to use chips.

Me and a buddy found a schematic for some form of latching system, with 4 buttons, etc. I built it in CircutMaker 6, but for whatever reason the circut only stays on for however long I hold the push button. Im not shure if that's a problem with the program or if the chip is wrong. Here's the schematic.

Here's another copy of a shcematic a freind made for me. If you can, please check it over so i dont build it, just to find out it wont work. (the L1-L4's are lamps, just there during the testing process, they will be replaced with relays when the circut is built.

Another Schematic

Some comments on your circuits:

Circuit based on CD4028 - this IC is just BCD-to-decimal decoder and there is no latch in it ..

In the second circuit you have some weird connectins - gate output to gate output - .. I don't think you should even consider this strange suggestion ..

The most recent circuit may work, however, I would add a monostabile to generate a nice clock pulse because you may have some timing problems as the clock is active on the rising edge, and 10kΩ resistors will not pull down TTL inputs, so you will have to replace 74174 with 74HC174 ..

Regards,
IanP

Relay Circut

The relay circuit looks OK ..
However, I would replace the small circuit with two diodes with four diodes (see drawing below) ..
Otherwise you will have to use aditional relays or find 5PDT relays ..
Regards,
IanP

Anyone have an explanitaion of how to wire that relay circut? It's kinda confusing me. First circut as an example, correct me if im wrong, which I probibly am. Circut 1 (top example on schematic)

+12 to button then to coil
+12 to CR1 ( any NO on relay 1) then that goes to CR2 ( any NC on relay 2) then that goes to CR3 (any NC relay 3) then to CR4 ( any NC on relay 4) then back to the +12v line that is going to the coil, then to ground.

Here's a REALLY messy copy of how i think it is wired. The color's are wires, for each push button...please follow the wires and tell me if i got the path correct for each. Now, does the small circut connect to the NO terminals on each relay corresponding to the correct circut? If that is so, I only need 1 relay for first gear, amung the relays used for the circut.

Jorgito, can you check over my last post, and does anyone have suggestions on how to make a PCB for this or should I use wires?