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NZeder 260z RB26 powered, triple DCOE throttle bodied NA project

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#161 NZeder


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Posted 01 January 2014 - 10:34 AM

Right long time between working on a zed - any zed of mine that is.

So I have done a little bit of work on both cars over the xmas break so far.

Some might recall that for the road car (the green one with steel flares) I was changing the cable operated heater for actuators from a later Nissan (just about any Nissan of the early mid 90's vintage) This is a push button control head with a variable resistor on the temp settings/slider. There is an electronic amp that reads the air temp in the cabin, the setting on the variable resistor and opens or closes the tap to control the hot water flow in the heater radiator. This amp also controls a series of relays to set the fan speed when in the auto mode.

Anyway the factory vent/airflow box from these later Nissans (N14, N15, P10 etc) usages just one actuator that controls all the modes - ie Face, Face/Foot, Foot, Foot/Defog, Defog. However I could not get this setup on the stock 260z Airflow box (the center bit the radiator in it) so the plan was to get it working with 2 actuators, the stock one and an additional vent door actuator from the same setup.

So the standard main actuator controls the standard center flapper door with the additional actuator controlling just the foot vent door. So the next step to getting this working was to work out how to control the foot door from the control unit - using a stripped down unit to expose the circuit board I worked out the how it operated on the bench - however using the feeds from the main actuator were not going to work as the power is removed once the actuator was in its correct position. This meant the foot door would not fully open or close before the power source was removed.

Plan B - use the LED indicators on the control unit and a custom circuit to control the foot door actuator as required. After 2 version of circuit (one using 5 transistors, resistors and diodes = big circuit board and one failed attempt due to me not thinking about + source as the trigger when I only had a ground trigger from the control unit...doh) a solution was found using a NAND Gate and some NPN transistors to turn on the actuator via its two ground connections.

The actuator has 3 wires to control it - +12V and the 2 ground points which position the actuator. 1 Ground point drives it 1/2 way around the other drives it the remaining 1/2 way back to the start.

The heater control unit grounds a spare pin to earth when the corresponding switch is depressed (LED is on at the same time). So these were used on my NAND gate inputs which were tied high with a pull resistor.

I used a 4023 triple NAND gate chip with all the inputs as stated pulled high by default which meant the output was low. When any of the inputs goes low (given only one switch only be depressed at once via a physical locking switch setup on the control panel) and the others are high then the output is high also (aka +12v). I used 2 of the NAND gates in the chip - one for the foot door close location and one for the foot door open. So now I had my outputs from the 4023 chip as required - when the foot door was to be closed (Face only button depressed, or the Defog only button depressed) then I would get a +12v on the corresponding pin on the chip and like wise for the door open (face/foot, foot, foot/def). Now I just needed to use a NPN transistor to take the logic +12v single and turn that into a ground on the load and connect that to the correct pin on the actuator.

Using a multimeter to meausre the current draw from the actuator I could then calculate the resistors I needed to drive the NPN transistor correctly (reads switch it on and off as required based on the output from the NAND gate).

Result = actuator control circuitry working as required for less than $20 worth of parts (including the 2 circuit board setup that were not ideal or did not work for the given requirements - 25 years since I last did electronics so I was expecting some errors in my thinking/circuit building.) If I build the correct circuit from the start cost would have been around $10 with most of the in the board and the box it sits in and only $4 of electronics.

So that is what I did on the road car.

Race car - installed the front brakes, attempted to install my rears - found out I had my rear brackets made up incorrectly = too thick on the ears = offset not right 1mm out = calipers did not fit. So I will need to get the brackets milled down by 1mm - but I will wait until I get the car to the fabricators shop and he can check it out himself, update his drawing and either fix these brackets. I started on the loom cut down, working on the rear loom first removing speaker wires, electric aerial wires, interior doom light and wires for the rear window demister/defogger (why would I need them in there on the race car given the screen in there does have one anyway). So that is a far as I got on them - 4 kids sock up so much time.....so next up is the rewire of the front loom with 2 circuits - lights/acc circuit/loom then engine loom - so I will have 2 looms going to the engine bay. The idea is that everything that is needed to run the engine is on separate loom - this way I can id issue faster and at the track who cares if the lights/horn etc are not working.

So not a lot to report but at least it is something (attached is an image of the internals of the ZC4023 that I used - I will post the full circuit once I draw it up from my hand drawn mess)

Happy New Year to all too.

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#162 NZeder


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Posted 10 September 2016 - 12:00 PM

Wow can't believe it has been that long since I last updated this thread.


1. All RB stuff gone.

2. 74 260z fully caged car gone and replaced with a 1970 Mini Cooper S replica (slow but lots of fun).

3. Nothing changed on the 76 260z road car - one day I will find the time and energy to put the kit set back together.


Things I need to do in the shed.


1. Tidy it up (always needs this).

2. Remove all the parts hanging on the wall - ie guards, bonnet, hatch etc.

3. Put building paper, insulation up then line the shed so it is not freezing in winter and too hot in summer (this is one of the reasons nothing is getting done + 4 kids aka time vampires as I call them).

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#163 Sirpent


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Posted 10 September 2016 - 12:23 PM

Was wondering where you had disappeared to  ;)


Dont fret, you are not the only one with a long term project LOL

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