Hello, I am new to the site. I was looking for a place where I could maybe learn how to make a circuit for something I am building.

I have some basic electronic component knowledge, but I will let you know if you are going beyond my level.

Basically, I have already made a manual control box for my car. It is an automatic transmission on my mitsubishi eclipse. In order to make the gears, all the transmission does it send power to 2 solenoids. Combinations of the solenoids getting power and not getting power makes the gears. All you have to do is send a 12v to the solenoid(s) to activate them.

So there are 2 solenoids... Solenoid A, and Solenoid B. These two solenoids control the gears like this:

GEAR: SOLENOID A SOLENOID B

1st ON ON

2nd OFF ON

3rd OFF OFF

4th ON OFF

So I made a prototype control box. I wired up two toggle switches and had a 12v power supply go to each switch. Then I would shift using the different combinations of switch positions as shown above.


Now for my question: Would it be possible to make a circuit that would use two momentary buttons (or paddles) that would be for UPSHIFT, and DOWNSHIFT? So when I push the UPSHIFT button, the circuit switches from powering both solenoids, to powering only one? And then when I upshift again, it switches to the next gear by sending power to neither solenoid? And then when I downshift I just push the button and it goes back down a gear?


Sorry for the long post, but how complicated would this be? ANY help would be appreciated! Thanks!

-Joe

 

Couple of things to check on. How much current do the solenoids pull? Can you override the normal control for shifting the tranny? And, does the tranny need some dead time between shifts so the old state can drop out?

 

Couple of things to check on. How much current do the solenoids pull? Can you override the normal control for shifting the tranny? And, does the tranny need some dead time between shifts so the old state can drop out?

The current draw I am not sure of. How can I find this out?

Yes I can override the normal shifting for the transmission. All I have to do is unplug the stock transmission control unit. When you send power to the solenoids manually, you have complete control over the transmission shifts, the stock control computer is just unplugged.

No dead time between shifts is needed. It can be changed instantly.

So with that, what kinda circuit am I looking at here? Difficulty level? Parts? Suggestions? Anything would be great, thanks!

 

No, the circuit shouldn't be too difficult, but a bit clunky if you can't make a printed circuit board. Do you want to be able to switch between stock and the paddles?

I've got people over tonight and some errands to run tomorrow, but I'll see if I can't put something together before too long. Someone else could jump in, too.

 

No, the circuit shouldn't be too difficult, but a bit clunky if you can't make a printed circuit board. Do you want to be able to switch between stock and the paddles?

I've got people over tonight and some errands to run tomorrow, but I'll see if I can't put something together before too long. Someone else could jump in, too.

Thank you very much! That would help so much, I really do appreciate it.

Honestly, if it makes the circuit a lot more complicated if I want to be able to switch between normal and paddles, just leave it out. I am just glad you can help me out in the first place, I don't want to make things more complicated for you.

As far as printed circuit board, would a component PC board from radioshack be ok to use if I cant get printed boards?

Thanks again, I am looking forward to trying out the circuit!

-Joe

 

It seems like one 3-position momentary paddle switch (mom-off-mom), controlling an up-down counter, would be better than 2 separate switches.

 

Nah, I would really like to do 2 paddle shifters that I can mount on my steering wheel. One for upshift and one for downshift.

So I researched a little and I would guess that I am going to need to use an IC chip for this? Does anyone know which one I use? And what terminals go to what?

 

How does neutral work?

 

How does neutral work?

Park, Reverse, and Neutral are all mechanically controlled by the shift selector lever. The shift solenoids are only used for forward gears. No matter if the solenoids are getting power or not when the car is in park, reverse, or neutral, nothing will happen, there will be no difference.

 

Looks like it could be done with an up/down counter and an XOR gate.

The switch contacts would have to be de-bounced as well to prevent skipping gears.

Required output:
GEAR A  B
  1st  1  1
  2nd  0  1
  3rd  0  0
  4th  1  0

For the count up/down, the 4029 would work; outputs would need post-processing...

4029
4-bit synchronous binary/decade up/down counter with preset and 
ripple carry output. 
     +---+--+---+
  PE |1  +--+ 16| VCC
  Q4 |2       15| CLK
  P4 |3       14| Q3
  P1 |4       13| P3
/RCI |5  4029 12| P2
  Q1 |6       11| Q2
/RCO |7       10| U//D
 GND |8        9| B//D
     +----------+

Use the XOR gate for post-processing

4030
Quad 2-input XOR gates. 
    +---+--+---+             +---+---*---+                    _   _
 1A |1  +--+ 14| VCC         | A | B | Y |       Y = A$B = (A.B)+(A.B)
 1B |2       13| 4B          +===+===*===+
 1Y |3       12| 4A          | 0 | 0 | 0 |
 2Y |4  4030 11| 4Y          | 0 | 1 | 1 |
 2A |5       10| 3Y          | 1 | 0 | 1 |
 2B |6        9| 3B          | 1 | 1 | 0 |
GND |7        8| 3A          +---+---*---+
    +----------+

Use the schmitt-trigger NAND gate for debouncing the switch contacts
4093
Quad 2-input NAND gates with schmitt-trigger inputs. 
0.9V typical input hysteresis at VCC=+5V and 2.3V at VCC=+10V. 
    +---+--+---+             +---+---*---+           __
 1A |1  +--+ 14| VCC         | A | B |/Y |      /Y = AB
 1B |2       13| 4B          +===+===*===+
/1Y |3       12| 4A          | 0 | 0 | 1 |
/2Y |4  4093 11| /4Y         | 0 | 1 | 1 |
 2A |5       10| /3Y         | 1 | 0 | 1 |
 2B |6        9| 3B          | 1 | 1 | 0 |
GND |7        8| 3A          +---+---*---+
    +----------+

Still working up a schematic

 

Thank you SgtWookie for the info! You said you are working on a schematic for me? That would be awesome, thank you very much for your time. I know I need a debouncer so it only goes one gear at a time, but I don't know anything about those or how they work. Hopefully I will be able to understand when I see the schematic! Thanks again!

 

I've got one, too. I'll try to get it posted up. Guess that makes it a race.

 

Cd40192 or 193 are up-down counters with separate up/down inputs. It seems like this would save a little up/down selection logic that has to be done with the 4029.

 

Thanks a lot guys! Can't wait to see them! Thanks again for you time

-Joe

 

Whoever designs this will need to know how much current the solenoids require. Do you know this? If not, can you measure the resistance with an ohmmeter or multimeter?
It would also be useful to know the make and model of the transmission.

 

Whoever designs this will need to know how much current the solenoids require. Do you know this? If not, can you measure the resistance with an ohmmeter or multimeter?
It would also be useful to know the make and model of the transmission.

Alright I just looked up the specs. The solenoids have a resistance of 22ohms.

This is for a Mitsubishi Eclipse GSX A/T transmission model w4a33.

 

The schematic is attached. It's a bit busy.

The main part is Z1, a CD40192 up/down counter. Pin 5 is the count up clock, 4 is the count down clock. It only uses the Q0 and Q1 outputs (pins 2 & 3).

Z3A & B are the upshift paddle debouncers. The output is low when active, so Z5A inverts for the clock. Z2A disables the up clock at 4th gear. Another count would put the states of Q1 & 2 to 0, which would select 1st gear - big no-no. The other debouncer is the same, but Z5B (mislabeled as Z9 - sorry) stops the down count at 0.

Z5C should reset the counter to 0 when power is applied. My favorite signal notation - power on reset not, or PORN.

The relays operate from the logic through the TO-92 hexfets, Q1 & 2. The relays (Coto 8L01's, Mouser part #816-8L01-12 @$1.57) are uncommitted, as I do not know if the solenoids need 12 volts fed to them, or ground.

I urge caution with this thing - there is no RPM input to lockout a downshift if the engine is turning too fast. Accidentally shifting to 2nd from 3rd at 5500 RPM will cause the engine to blow.

The circuit could be done with wire wrap, although a pcb would be spiffier.

 

The relays (Coto 8L01's, Mouser part #816-8L01-12 @$1.57) are uncommitted, as I do not know if the solenoids need 12 volts fed to them, or ground.

Thank you so much for helping me out with this.

The solenoids need 12 volts fed to them to activate them to shift. They already have a ground provided inside the transmission. So what would this change about the relays? Thanks

 

Just put 12 volts to one contact and the other to the tranny solenoid. When the coil energizes, the contacts close and feed the 12 volts the the solenoid.

 

Just put 12 volts to one contact and the other to the tranny solenoid. When the coil energizes, the contacts close and feed the 12 volts the the solenoid.

Alright, so sorry for the stupid question, but where exactly is the momentary switch in that circuit? Sorry, I am a little new to this stuff.