Amps

Lol, it's not that it's too complicated, it's just I like having my final system to be smooth and not hacked. I was thinking more along the line of a premade transmitter that I could build a receiver around.

Seems that each I look at has a safety switch somewhere in it to prevent the car from starting if brake/clutch isn't depressed. Anyone know of something else a little less complicated?

Ya, sounds good. I'll look into it and see if I can make it work.

I am completely new to the world of remote control and though I've spent 2 hours checking the net, I haven't found anything to fit my application. I'm working on desigining a Hot-Rod style computer case and one of the features I want is everything to be shaved and filled flush, including the power/reset buttons and the CD-ROM (only a small slot for loading). What I want is a small remote (pre-made preferably) that works on RF or IR that has at least 3 buttons that will control 3 seperate relays in a momentary switch configurations. I wouldn't mind building the receiver myself but I want the remote to look very nice. Any ideas on something I could use to accomplish this?

Ok, thats something I'll consider but I'll have to do more research. The motors in the circuit are just place holders for computer fans (circuitmaker didn't have a fan). I'm pretty sure that most computer fans have protection against that sort of thing otherwise everytime I switched on one of my many fans, my power supply would hiccup ;D

Oops, thats a small error on my part, I meant to put 5v relays in, just mis-clicked. Typical ambient temperature in my case will be about 15-20 degrees celcius. The way I have the resistance set up, that means that the controller will put out about 4.5-5v. These fans spin up at around 3.5v and it won't take long for them to hit the operating temperature of about 25-30 degrees. You mention putting a diode across the fan but I've never had to do that for a project such as this before. Can you explain? I've got the 2 across each coil on the relays.

Ok, here's the revised circuit. The circuit will be controlled by a regular switch so current limitations shouldn't be an issue. Thanks for all the help MP ;D

Thanks a lot MP. I've considered all the options and I think that for the sake of simplicity, I'm going to go with 2 DT Relays connected to a DPST switch. Here's an image of the schematic I've figured out. The only thing different from the final schematic is the variable resistor to the LM317 will be a 500ohm thermistor. One thing I'm not sure about but have heard about is back EMF for the relays. Apparently I should toss a Diode in somewhere?

Well see, I'm not just switching from 12v to 8v. Lemme see if this helps: Switch Position 1: -Intake Fan powered by a temperature control circuit. Approximately 6-10 volts varrying between 25-40 degrees celcius will be applied to the intake. The 8v in the schematic was just a place holder so I could test the circuit in my software. -Exhaust Fan is off, no power. Switch Position 2: -Intake AND Exhaust fans are both receiving a full 12 volts. My original reasoning for using the 4N25's was because I couldn't figure a way to controll both fans with one switch but have one fan controlled by 2 sources and the other off/on without crossing the power lines somewhere. With the isolators, I don't have that issue.

Well see, thats why I had to come here to ask. I can't make sense of anything on the datasheet as far as limits goes. I'm just not into the lingo :( The fans will probably be drawing no more then 1.5 amps total (the exhaust will be 2 high cfm fans) and I'm really not sure if that will burn up the chips, which means I'd need to find a high current version of the 4N25.

Both fans will be designed to run at 12volts but the intake fan will be scaled down when the switch is in the first position to run close to 8volts.

Hey guys. I plan on controlling 2 fans, 1 Intake and 1 exhaust, for cooling in a computer case. I want to have one DPST switch that when in one position will cause an 8v (eventually a temperature controlled circuit instead) to power only the Intake fan and when in the second position, both fans will receive a full 12v. I decided to use 4N25 optoisolaters simply because it would isolate the 2 fans completely but I've never used something like this before. I made this schematic in Circuitmaker2000 and it seems to work on there but I really have no idea what the tolerances of this circuit would be or if maybe I'm doing something wrong. If you guys have any suggestions, please lemme know.

Thats great guys. One question though: What is the resistance range on the DS1669? I can't seem to find it on the data sheet. <EDIT> Nevermind guys, was looking at the wrong datasheet. Looks like I can get it in a nice 10k flavour </EDIT>

Hey guys! I've spent 3 hours researching different DPPs (digitally programable potentiometers) but everything I find seems too overkill for what I need. Here's my cicuit idea: The CPU cooling fan in my computer operates from 3000-7000RPM using a small pot wired into a simple LM317 circuit ranging from 5v to 12v. I want to be able to find an electronically controlled pot that I can control through two momentary switches (up and down). Is there an IC that someone knows that I can use to do this? If so, would you mind giving me a quick rundown on how to control it and set the range? My electronics knowledge is slim (only grade 10 electronics) but I have a great problem solving mind so if I can get some simplified terms, I can work from there. Thanks guys!