Why do we use PWM control?

Started by Gundal21 in sci.electronics.basics8 years ago 3 replies

I always feel thanks to all of the group members. Today I'd like to ask some basic question (the group title is basic). As is shown in the...

I always feel thanks to all of the group members. Today I'd like to ask some basic question (the group title is basic). As is shown in the title, I don't exactly know why we use the PWM. I think that all the works PWM can do can be done by the DAC and linear power amplifier. Of course, the price may be up. But then I am curious again that the price is the only reason for us to use the PWM...


Linear regulator

Started by Jonas in sci.electronics.basics8 years ago 6 replies
PWM

Hello HAs anyone ever tried to use a linear regulator to regulate a PWM signal? My situation: Input signal, 24V PWM 400Hz I want to have...

Hello HAs anyone ever tried to use a linear regulator to regulate a PWM signal? My situation: Input signal, 24V PWM 400Hz I want to have 12V PWM signal 400Hz I was thinking of using a linear regulator (type LM317) and use the 24V PWM as input and get 12V PWM on the output, does anyone know of any problems related to this (lifelength, EMC etc). /Jonas


Zener and rgulator

Started by lerameur in sci.electronics.basics11 years ago 12 replies

HI, I am doing a battery charger using PWM. The circuit is controlled by a PIC chip, which will control a transistor in PWM to charge a 12v...

HI, I am doing a battery charger using PWM. The circuit is controlled by a PIC chip, which will control a transistor in PWM to charge a 12v lead acid battery. The voltage will be taken diectly from the outlet and recified (approx. 150vDC) using PWM I can get 13.8 volt for charging. The question is how do I power my pic chip which requires 5v? 1 ) I though of adding a small battery, but i w...


thinking about a 200 amp 12v pwm controller

Started by izzi in sci.electronics.basics9 years ago 2 replies

I"ve started looking into putting together around a 200-250 amp 12v pwm controller for a DC drive i have. I've got the pwm driving aspect of...

I"ve started looking into putting together around a 200-250 amp 12v pwm controller for a DC drive i have. I've got the pwm driving aspect of this down aside from the mosfet selection and dealing with the heatsinks that i'll be stuck using. Anyone ever put something along these lines together before? The cycle time will be low around 1 min on and very long time off. 30min+ range, this s...


PWM lighting quest!

Started by ...Ad! in sci.electronics.basics11 years ago 14 replies
PWM

Hi! i'v got two 12v halogen lamps connected to a single supply, not strong enough to drive both together. It's heard that enough brightness...

Hi! i'v got two 12v halogen lamps connected to a single supply, not strong enough to drive both together. It's heard that enough brightness can be obtained using PWM driven FETs. need help... Bazz ...Ad!


PWM controlled current sink for LED backlight.

Started by Sean Peters in sci.electronics.basics9 years ago 12 replies

Hello, I have a monitor with a LED backlight that uses PWM to directly switch on/off the LEDs to vary the brightness. I can't stand the...

Hello, I have a monitor with a LED backlight that uses PWM to directly switch on/off the LEDs to vary the brightness. I can't stand the flicker this produces and want to modify the LED driver to keep the LEDs on all the time, setting the brightness by limiting the drive current, depending on a smoothed version of the PWM signal. I've kind of managed this already, but can't get the ful...


PWM

Started by Anonymous in sci.electronics.basics11 years ago 7 replies
PWM

Can anybody tell me how to make a simple PWM?

Can anybody tell me how to make a simple PWM?


DAC from PWM

Started by Anonymous in sci.electronics.basics11 years ago 1 reply
PWM

Hello All, I need a simple DAC from a PWM on a PIC. What is the name of the circuit I need to search for? Thanks, John

Hello All, I need a simple DAC from a PWM on a PIC. What is the name of the circuit I need to search for? Thanks, John


PWM from raspberry pi to control charging of a 12 V Battery, possible?

Started by Anonymous in sci.electronics.basics5 years ago 2 replies

Hi there, I just got a raspberry pi and was wondering if it is possible to use its PWM output to control current flow to a 12 V Battery (with...

Hi there, I just got a raspberry pi and was wondering if it is possible to use its PWM output to control current flow to a 12 V Battery (with an IGBT). My idea is to use a 300 W windmill, a simple AC/DC converter, a IGBT, and the battery at the other side. If voltage is above 13.8V, I reduce the current via PWM to fully charge the battery and disconnect the windmill as soon as the battery ...


run 6V DC motor @ 12V w/ PWM ?

Started by 1jam in sci.electronics.basics7 years ago 5 replies

If I run a 6 volt dc motor at 12 volts, using less than 100% PWM, will it be ok? or will it still burn out. thanks

If I run a 6 volt dc motor at 12 volts, using less than 100% PWM, will it be ok? or will it still burn out. thanks


PWM vs Analog Output

Started by leve...@gmail.com in sci.electronics.basics11 years ago 6 replies
PWM

Hi all, Thanks for everything that you write before i have learnd a lot of from this group. I am designing a circuit which uses a 18f452...

Hi all, Thanks for everything that you write before i have learnd a lot of from this group. I am designing a circuit which uses a 18f452 and DAC0800 for analog output. Each DAC drives an TIP31 type BJT. Could we use this analog signal to control a DC motors speed? will this be efficent as PWM ? If not so why not ?:) Thanks for reply?


Increasing PWM output voltage

Started by Dave, I can't do that in sci.electronics.basics9 years ago 12 replies
PWM

Hello, I need to boost a PWM signal at 5KHz and 450mV to 5V at 5KHz and 100mA max. Could someone please give me a list of the components I...

Hello, I need to boost a PWM signal at 5KHz and 450mV to 5V at 5KHz and 100mA max. Could someone please give me a list of the components I need and a schematic to do this. A suggested idea was this... http://www.cnczone.com/forums/showpost.php?p=501327&postcount=4 But as you can see the guy was unsure of N-channel or P-channel and he never got back to me. Thank you. Dave


3vdc motor PWM problem

Started by randomname in sci.electronics.basics11 years ago 35 replies

hi all. i posted awhile back about my time fountain project, everything is up and running! it works beautifully (for a few seconds, read on)...

hi all. i posted awhile back about my time fountain project, everything is up and running! it works beautifully (for a few seconds, read on) with my new submersible dc motor pump. if you dont remember the project, heres the deal: I need a constant drippage of water. I do this with a 3v dc motor, which pumps through a tiny valve then out the tube. its PWM with the following: 555 timer,...


Simple PWM Circuit for motor control

Started by Anonymous in sci.electronics.basics11 years ago 9 replies

I need a simple PWM circuit to control a motor from my microprocessor, I found this one: http://home.cogeco.ca/~rpaisley4/LM555.html#17 Any...

I need a simple PWM circuit to control a motor from my microprocessor, I found this one: http://home.cogeco.ca/~rpaisley4/LM555.html#17 Any comments? It looks cheap and simple to build so should fit my requirements.


general question about pwm and brushless fans

Started by default in sci.electronics.basics8 years ago 9 replies

I have a fan I want to use with continuously variable speed. It is a brush less type (specs on this one say 7-12 volts) should work. And it...

I have a fan I want to use with continuously variable speed. It is a brush less type (specs on this one say 7-12 volts) should work. And it does . . . but won't take PWM directly, it wants to see steady voltage not chopped. I tried frequencies from 20 kHz to 1 kHz 1. Is this typical? 2. Anyone else with experience, of speed control of generic brush less fans? I tried my circuit w...


Adjusting frequency NE556

Started by Dave, I can't do that in sci.electronics.basics9 years ago 13 replies

Hi, The following is a PDF of a motor control kit... http://www.electronickits.com/kit/complete/motor/ck1400.pdf Currently it is designed...

Hi, The following is a PDF of a motor control kit... http://www.electronickits.com/kit/complete/motor/ck1400.pdf Currently it is designed to run at around 410Hz. I assume that too will be the frequency for the PWM output but I need 5KHz from the PWM. I looked at the formula for frequency on page 1 and it may as well be written on Chinese as far as I can tell. Could someone with...


Filtering a PWM signal

Started by Bob Engelhardt in sci.electronics.basics5 years ago 4 replies

I've been watching some of Dave Jones videos (EEVblog). In #225 he discusses using a PWM signal to control the voltage of a power supply. It...

I've been watching some of Dave Jones videos (EEVblog). In #225 he discusses using a PWM signal to control the voltage of a power supply. It needs to be DC to do this, so he uses a filter. He uses a first-order RC filter, with the output going to the "+" input of an op amp. With a 10% duty cycle on the input he shows the output at 10% of the input peak, with some ripple. What I don'...


555 Timer Duty Cycle

Started by Michael in sci.electronics.basics11 years ago 5 replies

Hi, I'm trying to use a 555 timer to produce a PWM waveform however can't find any reference as to how the value of the resistor* can be used...

Hi, I'm trying to use a 555 timer to produce a PWM waveform however can't find any reference as to how the value of the resistor* can be used to calcuate the duty cycle. Is there a formula that says something like when you use Xohms it gives 2X% duty cycle? Cheers, Michael *http://www.scienceprog.com/control-motor-pwm-schematic/


Driving a PNP Darlington transistor from a PIC16F877A

Started by scouselad in sci.electronics.basics10 years ago 5 replies

Hi, I'm designing an electronically-controlled light dimmer circuit based on one I found at: http://www.edn.com/article/CA46649.html I'm...

Hi, I'm designing an electronically-controlled light dimmer circuit based on one I found at: http://www.edn.com/article/CA46649.html I'm replacing the SG3524 PWM chip with a PIC16F877A and I intend to take a digital input from the user and (scale it, then) compare it with the 0-5V from the op-amp (digitised using the PIC's ADC). As you can see from the diagram, the PWM signal drives a PNP ...


pwm need to increase frequency

Started by amdx in sci.electronics.basics9 years ago 5 replies
PWM

I have built the PWM circuit located here, http://www.cpemma.co.uk/pwm_erg.html The triangle osc. frequency is about 150 hz. I want to increase...

I have built the PWM circuit located here, http://www.cpemma.co.uk/pwm_erg.html The triangle osc. frequency is about 150 hz. I want to increase it to about 15 khz. When I changed the capacitor, C1 and resistor, R1 the waveform got very distrorted. The risetime of the waveforms was slow. Are there adjustments that can be made to make the circuit work at 15 khz? Or is the LM 724 to slow for ...