Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Power supply question

Status
Not open for further replies.
i was talking about them running different out the box!! not once there installed. i check all fans before they are installed, and theese days all fans are monitored for RPM, back pressure is negliable in the incubators, but there again 3v0 and myself spent a great deal of time on theese incubators over the last couple of years. things are pretty solid now but will change this winter when i do a complete overhaul and redesign, the only thing that will stay the same is the fan controller.
anyway my advice to the OP is check his fan dont rely on the datasheet and personaly i would keep the blades on as its not easy to remove alot of them and can lead to them running off centre.
 
They should never run different out of the box or your fan quality is really low. I'd like to see how the fans are positioned, any significant object within 1-2 times the diameter of the fan blades will cause back pressure, especially if it's from ambient pressure to an enclosed environment. So unless your fans are free and CFM in and out is measured, clear to that distance there's a whole lot more going on than you're aware of.
 
Last edited:
Ok so any wire thats the same width or greater will power the fan and I should cut off the blades that Im not going to mount the magnets on. The alternatives to the pot you suggested sound quite complicated so unless you want to advise me further I guess I will just go with one of them. Actually I see that radio shack has a 3 watt rheostat for $4 so I am gonna go that route. I am probably going to check the width of wire on that old dvd player first. Does it sound like im on the right path?
 
Sounds like the right path. Good luck with the project.
 
The 3 watt rheostat will work but what's it's maximum ohm value? You want pretty low, otherwise a large portion of the range of motion for the dial will be lost. Anything higher than 1k and your usable range is going to be a fraction of the arc of the dial. Even with 1k the dial will be exponential, meaning a little bit of motion on the dial will drastically cut power quickly. If the value of the rheostat you pick up is too high it'll be extremely difficult to actually control the speed.
 
Rheostat wattage is determined by circuit current and rheo. resistance.

P = I^2 x R

Different combinations of I and R will obviously require different values of P.

DC motor startup current is easily figured by dividing applied voltage by short ckt resistance of the motor. My radiator fan is about 136 amps, calculated and measured.
 
Last edited:
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top