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Posted by The Max (92 J30 Maxima (turbo project underway)) on August 20, 2002 at 02:49:50:
Note the really cool Dream Theater CD beside it!! 3#-) The buzzer is obviously the largest part of the unit's side profile. Forgive the heatshrink, but it looks like custom polycarbonate housings are the answer to this. So being a prototype, heatshrink was the go. Unfortunately, the circuit board lost its centering in the shrinking process and needed electrical tape to cover the one slightly exposed side. Now for the connections: A constant 12V power source was nominated in order to minimise complications that may arise from vehicles with remote starter units of varying configurations. This helps eliminate a lot of guesswork. Start signal is required to ensure the turbo timer that we're definitely attempting to get the motor going. This is a preferable alternative to tapping into the tach signal as inexperienced installers can locate a start wire easier than an ECU wire, I'm sure. Ignition signal is monitored to ensure that we're not apply power to the ignition line when it's not desired! It's a safety measure above all else. Accessories is monitored to actually initiate the timing process, taking the timer out of its standby mode. If oil pressure should drop, or the handbrake should be released when the footbrake is not applied after accessories has been switched off (i.e. when the turbo timer is actively timing), at the expense of the turbo, the vehicle is switched off. This is a very crucial safety measure. I'd rather destroy my US$1500 turbo than wreck my entire vehicle, let alone the motor. If the temperature is satisfactory, the turbo timer runs for at least 1 minute to just keep things nicely lubed before powering down. Otherwise, so long as the 1 minute minimum time requirement has been satisfied, the vehicle will be shut down once the temperature has reached the desired point. The temperature threshold is adjusted with a fine flat blade screwdriver. Note in the side profile photo where the red LED is, there's a little hole with a brass screw in front of it. That's the adjustment pot. When the desired threshold is reached, the red LED will turn off from that point and below. So the idea is, when your turbo is at the desired temperature, adjust the screw so that the LED *JUST* turns off. The status LED indicates when the turbo timer is on standby (constantly on) and when it's in active mode (flashing at a rate of 2 times per second). In active mode, there is an audible beep at the same rate in conjunction with the LED's flashing. Should the vehicle be switched back to ignition during the active warm-down process, the turbo timer will return back to its standby state after 10 seconds. Otherwise, if you have a quick change of heart within those 10 seconds, it will continue to perform as though no change occurred. Should you want to force the turbo timer inactive, that's what the Reset button is for. That's pretty much all there is to it. Can you guys think of any refinements I should make to it (apart from the next design not requiring an EGT gauge)? I'm thinking something like this should sell for no more than about US$40 complete with relay and wiring. What do you guys think?
...for those of you interested in what I might be possibly marketing and at a cost much cheaper than any other turbo timer out there, with the only downside being you need an EGT gauge in your vehicle as well.
Battery
Ground
Accessories
Ignition
Start
Relay
Handbrake switch
Footbrake switch
Oil Pressure switch
Temperature (monitored from EGT gauge's signal)
Status LED
Reset button