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Author Topic: Owm pwm-control from a step by step guide  (Read 1609 times)

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Offline assassa1221Topic starter

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Owm pwm-control from a step by step guide
« on: April 09, 2013, 03:30:51 AM »
I made this: Problem is maxium current is only 0.2A.
http://www.easterngeek.com/2008/06/simple-and-dirty-pulse-width-modulation.html

This professional shop's PWM have maxium of 15A
http://dx.com/p/dc-6v-90v-15a-pwm-motor-speed-control-switch-governor-green-black-160094

WHAT TO ADD and HOW TO PLACE COMPONENTS TO MINE:
  • 6V or 12V BATTERIES PACK 18650(2x or 3x)
  • max. amperes safe about 3A ???
(Controlling geared 12V high torque DC motor)
LIKE THIS FOR EXAMPLE: http://dx.com/p/high-torque-60rpm-12v-dc-geared-motor-91625

A LIST OF WHAT TO BUY(with ratings W,V,A) and a drawing how to solder things...
 
Thanks  :D

Offline newInRobotics

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Re: Owm pwm-control from a step by step guide
« Reply #1 on: April 09, 2013, 04:50:32 AM »
Hi :)

To make 555 timer PWM generator circuit 3A capable You only have to add 1 PNP transistor (able to provide 3A at 12V) and 2 resistors (pull-up resistor of 10k and base resistor which value is calculated using hFE value of Your chosen transistor (base transistor should not allow more that 0.2A to go through 555 Timer)). Take a look at simulation here --> 3A capable 555 timer PWM generator (requires Java to play) or at the image attached.

P.S.
It wouldn't hurt You to understand more about transistors (read and try to comprehend all 8 pages)
--> Bipolar Transisthttp://www.electronics-tutorials.ws/transistor/tran_1.html

Also, here's a good article on how to calculate base resistor value
--> http://www.physics.unlv.edu/~bill/PHYS483/transbas.pdf
« Last Edit: April 09, 2013, 04:57:23 AM by newInRobotics »
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Offline jwatte

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Re: Owm pwm-control from a step by step guide
« Reply #2 on: April 09, 2013, 12:28:30 PM »
For PWM, you really want MOSFET transistors. And, to drive MOSFET transistors, pull-up/downs isn't enough; you want to use a MOSFET driver.
I would use something like an IR2301 as the driver, and a high-end N-channel MOSFET switch. Any high-power MOSFET will work fine; for example the PSMN022 is cheap and capable.
http://www.digikey.com/product-detail/en/IR2301PBF/IR2301PBF-ND/812114
http://www.digikey.com/product-detail/en/PSMN022-30PL,127/568-7512-5-ND/2606361

So, you'd wire the 2301 according to the data sheet (two capacitors, one diode) and the 555 timer to the input of the 2301, and then the output of the 2301 to the gate of the MOSFET. Finally, the MOSFET switches the power for the thing you're driving. With the PSMN022-30PL, you can switch about 15V at 15A safely (it's rated for 30V at 30A.) With a slightly more expensive device, you can drive 30V at 30A or more (50V at hundreds of Amperes if you get the right MOSFET.)


Offline assassa1221Topic starter

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Re: Owm pwm-control from a step by step guide
« Reply #3 on: April 10, 2013, 05:00:53 AM »


  • First what input voltage and ampere range can I use this PCB now ?
  • Base resistor value ? TIP32C
  • Why pull-up resistor value 10kΩ ?
  • Minium power(W) for resistors should I order 2W for safe solution ?
  • Will these components protect the circuit pcb for any "weird harms" that I haven't though of ?
    • Capacitor voltage 25V ok ?(104 Ceramic disc)
    • Diodes Current 1A ok ? (1N4007)
    • Any other...Hmmm... ???
Next I'll try to draw that same with those Mosfet"jwatte".
  • Someone said motors"buzz\whine" with some frequenzes\components. How to make it as silent as possible ?
« Last Edit: April 10, 2013, 05:41:41 AM by assassa1221 »

Offline assassa1221Topic starter

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Re: Owm pwm-control from a step by step guide
« Reply #4 on: April 10, 2013, 06:14:21 AM »
I tried drawing MOSFETS+DRIVER from datasheet but... nääh...didn't work out... :'(
- Could "jwatte" complete drawing below ? (post it to photobucket.com, flickr.com or such... free photosite)
Thanks ::)
- What are common names for DRIVER: IR2301PBF MOSFET: PSMN022-30PL,127 when searching EBAY.COM or chinese sites like DX.COM where to get these ? (Shipping Europe payment paypal.com )
« Last Edit: April 10, 2013, 06:25:17 AM by assassa1221 »

Offline jwatte

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Re: Owm pwm-control from a step by step guide
« Reply #5 on: April 10, 2013, 04:53:27 PM »
In your first design, the transistor is going to waste a lot of power. 25V may or may not be enough. If your battery voltage is 12V or less, you're probably OK.

In the MOSFET and driver data sheet designs, each of the capacitors can be a 100 nF capacitor, at 25V or higher. The diode can be a common small-signal 200 mA fast recovery 25V rectifier like an 1N4148. The resistors should be about 5-10 Ohm or so, and 1/4W is fine, because the duty cycle will be low.

If you don't like the particular devices I showed links to, I would recommend searching for "N-channel power MOSFET" for the transistor, and "MOSFET driver" for the driver IC.

In the data sheet, there are two MOSFETs, because it's intended to be used as one half of an H-bridge (so you can run the motor both directions.)
If you just need to switch a single MOSFET, you could hook it up low-side (between the motor and ground) and you don't need the diode and high-boost capacitor.

Another decent MOSFET driver for low-side-only is the MCP1407: http://www.digikey.com/product-detail/en/MCP1407-E%252FP/MCP1407-E%252FP-ND/1228640

As far as suppliers go, I would recommend against eBay. Just get the parts from your local distributor. If you're in Europe, Farnell or RS-online are fine electronics distributors.

Offline jwatte

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Re: Owm pwm-control from a step by step guide
« Reply #6 on: April 10, 2013, 05:42:00 PM »
Here's a diagram using some N-channel MOSFET and the MCP1407:



You could also drive the 1407 directly from 12V (as high as 20V if you want) and probably get even faster switching on the MOSFET. That would matter if you were driving 10A or more.

The gate resistor can be 1 Ohm at 5V, and 2 Ohm at 12V, but you could also do without it. It doesn't need to be more than 1/4W because the duty cycle is very low.
« Last Edit: April 10, 2013, 05:45:46 PM by jwatte »

Offline assassa1221Topic starter

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Re: Owm pwm-control from a step by step guide
« Reply #7 on: April 11, 2013, 03:33:13 AM »
  • Where goes those two(2) wires marked with "?"
  • In simple words I just need to add:
    • 1x Driver
    • 1x MosFet
    • 1x Capacitor 104
    • 1x resistor Not needed

  • Is potentiometer 2W good or can I choose even lower rating ?
  • Is diode 1N4007 1A enough ?
  • Input voltage range ?
  • Max. amperes that handles ?
  • Can I insert just DPDT-switch to motor's(+,-) to change direction ?

Can't buy from Fernell.com I don't have a company just private person Could you pick from below links some good alternatives ? (Price as low and as many pieces as possible)
[/list][/list]
« Last Edit: April 11, 2013, 08:37:38 AM by assassa1221 »

Offline assassa1221Topic starter

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Re: Owm pwm-control from a step by step guide
« Reply #8 on: April 11, 2013, 03:44:48 AM »
I really like to make my own but in the meantime waiting postage...I'd like to ask...
Are these MOSFET+DRIVER types the one i'm trying to build or is mine even better ?(See links)
Are these cheap chinese PWM-alternatives unreliable and dangerous ?

Offline jwatte

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Re: Owm pwm-control from a step by step guide
« Reply #9 on: April 11, 2013, 01:06:32 PM »
Farnell should sell to regular people, too. Just write "self" for "company name."

If all your potentiometer does is regulate the 555 timing, I imagine a 1/4W potentiometer should be sufficient. The reason those pictures use a higher current one is likely that those are also higher-durability when operated a lot.

You *can* change direction with a DPDT switch, but you'd probably rather want to use an H-bridge for that.

A 1N4007 is overkill, and actually won't work as well as a smaller, fast-recovery diode. Although it will probably work well enough.

There are no wires marked "?" in the diagram; there are components marked "?" because there was a bug in the schematic capture program I used that didn't let me edit the component names. C?, C? and R? are really C1, C2 and R1. There are no un-marked or un-terminated connections on the diagram I posted. The diagram I posted will drive a 50A motor if you use the right MOSFET transistor -- it's all in the MOSFET at that point. Btw; A MOSFET with a low Rdson will not even need heat sinks. I don't understand why the PWM controller you're linking to uses heat sinks -- maybe they use bipolar transistors? It doesn't even make sense to use cheaper MOSFETs with higher Rdson, because the cost of the heat sink components and assembly is likely more than the price difference to a good MOSFET that doesn't need heat sinks. Perhaps they're not using a MOSFET driver at all, and spend too much time in the transition region, which would heat up the switch?

 


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