Electronics guys?

[Daox]

Anyone here know a few things about electronics? I have a circuit I'm looking into building and could use some help. Its a simple circuit, but I don't know quite enough to finish it!

[roflwaffle]

http://www.electro-tech-online.com/

[MetroMPG]

Whatcha makin'?

[Daox]

I'm looking into building an electronically actuated grill block. The first reason is for aero. The car is mostly driven on the highway and any aero mods will help. There is also the benefit of quicker heating from cold. As it is, the Matrix heats up pretty good with the block heater. But, there is still a lot of open space under the engine bay and between the bumper cover and the main radiator support. I've noticed the engine cooling off if idled at a stop for a descent length of time with the heater on in very cold weather. This is even with the two grill blocks I have in place now! So, I would like to add under paneling between the bumper cover and the area directly under the engine. This would leave only the gaps at the front of the vehicle, and the very rear of the engine bay open. I'm expecting this to overheat the engine fairly quickly. So, I'm looking into electronically actuating an opening to cool it off when it gets too hot. The setup is very simple (and relatively cheap), but the circuit to control the actuator is just out of my limited electronics knowledge.

[TomO]

Can you post up a schematic so the electronic gurus can have a look-see? Is it going to be thermostatically controlled or just a toggle switch?

[MetroMPG]

I'm no electronics expert. But having read a bit about the Arduino (relatively inexpensive, open source, programmable microcontroller), it might be the path I'd pursue for something like this.

E.G. here's an Arduino being put to use for temperature sensing & control: Arduino Beer Thermostat

Sean shows us how to use an Arduino for kegerator temperature control. A Kegerator is a beer keg built inside a refrigerator. Anyone want a cold beer? He discusses the home brewing process and how a microcontroller can be applied to this and many other sensing and control task. Man I’m thirsty now…

[Daox]

I'll explain what I had in mind for the electronics gurus. I don't have any specific diagrams though.

The system uses a very simple actuator. It is actually an power door lock actuator. Its a simple 2 wire device. Put 9V in one wire and it goes out, 9V in the other wire and it goes back in. There are no stop switches inside of it, so if you keep putting 9V in it keeps trying to go out/in. So, it requires the use of a timer. Roughly 1 second is enough to complete the throw of the actuator in either direction. This is what I don't know how to do. I was looking at using the 555 IC. But, I haven't found anything that exactly fits my situation, and I don't know enough to customize one myself.

Controlling the actuator will be a coolant temperature switch. Something similar to this. Of course, all this does is throw a switch. So, I was thinking that using a DPDT relay would be enough to switch the ground/power to reverse the actuator. However, the timer must be used to stop the power flow to the actuator once it is done moving.

Make sense?

I don't really want to get into programmable chips. It should be simple enough to do with standard ICs.

[Daox]

Alright, this is a rough idea of what I am thinking. I don't know all the proper symbols, but I think it gets the point across. I don't know if this'll work this way, and obviously the timer is going to need a trigger of some sort.

[TomO]

OK, I believe I understand what you are shooting for: Using the lock actuator that you already have in hand to open/close the "flap" panel that you are going to install under the front of your car.

With what you've stated about the actuator "It is actually an power door lock actuator. Its a simple 2 wire device. Put 9V in one wire and it goes out, 9V in the other wire and it goes back in. There are no stop switches inside of it, so if you keep putting 9V in it keeps trying to go out/in.", let me propose this to you: Why not use the 12V available in your car already and use a DPDT momentary rocker switch directly attached to the lock actuator? It's simple and very cost effective, but does require you to pay attention to the engine temperature. If you are set on it being a completely automatic affair, I can understand that.

If you are set on going the completely automatic route with the programmable controller, it seems like a good route to go with that Arduino controller, as long as you're good with programming. You could use a thermistor placed against a radiator hose for a temperature input and program the Arduino for a set time limit of power to the lock solenoid. You should be able to easily set up one out put for close and another output for open based on temperatures.

So my next question is: how good are you at programming?

[Daox]

I'm not the primary driver of the car, so it needs to be automatic. The consequences of it not opening up are not good if someone else doesn't know what to do.

I'd like to stay away from the programmable controller. I'm familiar with programming and leanring the language probably wouldn't be a big deal. But, I don't think I should need it. Plus, I don't want to have to buy the extra equipment. The thermal switch will tell the door when to open and shut. The timer just needs to break the connection 1 second after the thermal switch turns on or off.

After reading a bit I might just be able to use a SPST one or single shot relay? I just read about these and know nothing so far.