# How can you add 30% frequency on an output of a microcontroller?

#### nestbulala

Joined Dec 12, 2015
111
I have a controller for an air conditioning unit but the speed of the fan was very slow. The motor controller was being controlled by a triac which is triggered from a microcontroller through a transistor and an optocoupler. The frequency changed as the speed change but it is not enough to drive the motor to a certain speed. I need to be able to add about 30% of the frequency output to be sent to the triac to increase the voltage. Is there anybody that can help me out of this? I'll appreciate it very much any help you can contribute on this matter. Thank you very much guys.

#### ScottWang

Joined Aug 23, 2012
6,926
I thought a circuit as quadruple of input frequency and divide by 3, it can be get about 133% of input frequency, but this circuit will using the capacitor and it will be affected by the frequency, so if the range of frequency is too large then it will needs the switches to switch different frequency.

#### mcgyvr

Joined Oct 15, 2009
5,394
replace the controller?
How do you know its not the speed its designed for and there is nothing wrong with it?

#### nestbulala

Joined Dec 12, 2015
111
replace the controller?
How do you know its not the speed its designed for and there is nothing wrong with it?
The controller is programmed for a certain speed for a certain motor. I want to use it in my motor but it is not to the rated speed or voltage that my motor needs. Say it is programmed for about 70 percent duty cycle. I want to change the frequency to 95 or 100 percent duty cycle. What circuit should I use to do that.

#### joeyd999

Joined Jun 6, 2011
4,425
Change the crystal! (This is a tongue-in-cheek proposal...assuming it even uses a crystal).

#### nestbulala

Joined Dec 12, 2015
111
Dear Joey,

There is no crystal, it uses a voltage controlled oscillator and a 60 hz frequency as a time base generator.

mcgyvr,

If we will replace the controller, then we will be having problems on the programming. I need only to be able to change the voltage on the output of the triac to about 160 Volts at low speed, 185 Volts at medium speed and 200 Volts at high speed.