Good day all.
I need some advice plse. I have a motor that is mounted on a rotisserie, It works from 3Vdc ( 2x 1.5V batteries in series). I want to make an adjustable circuit between 3 to 5Vdc to drive the motor without having to worry about batteries.I have 12V 1.5A smps's that I want to use as they are small.
the resistance of the motor is 2.8R, meaning the current will be 1.071A at 3V and 1.78A at 5 volt. Watts drawn will be 3.21 and 8.9 watt respectively.
I have used a 11R 25 watt resistor as a voltage divider to test, The voltage is almost 3Vdc but the resister gets hot soon. What would be the easiest way to control the motor without having to use a bulky circuit, well I can all way's use a long connecting lead. This is what I have in mind, Would be using a mosfet work better ? Help appreciated🙂
I need some advice plse. I have a motor that is mounted on a rotisserie, It works from 3Vdc ( 2x 1.5V batteries in series). I want to make an adjustable circuit between 3 to 5Vdc to drive the motor without having to worry about batteries.I have 12V 1.5A smps's that I want to use as they are small.
the resistance of the motor is 2.8R, meaning the current will be 1.071A at 3V and 1.78A at 5 volt. Watts drawn will be 3.21 and 8.9 watt respectively.
I have used a 11R 25 watt resistor as a voltage divider to test, The voltage is almost 3Vdc but the resister gets hot soon. What would be the easiest way to control the motor without having to use a bulky circuit, well I can all way's use a long connecting lead. This is what I have in mind, Would be using a mosfet work better ? Help appreciated🙂
Attachments
You can use the ubiquitous SG3524 PWM chip (Various versions) -- to drive MOSFETs. Lotsa schematics on the web.
The motor controller in my Durst Printo failed and I built a PWM controller which torqued the motor just using a single potentiometer. Chip was TI's LMD18200 but these have gotten really pricey. L6203 used to be a favorite of DIY CNC guys for stepper motors.
Or buy ready built off Ebay - so cheap, not worth making your own.
Unless you can limit the top speed you might want a 5V supply or use a DC-DC step down buck regulator to reduce your 12V down to 5V.
Unless you can limit the top speed you might want a 5V supply or use a DC-DC step down buck regulator to reduce your 12V down to 5V.
Thanks for the info guy's, to order a module takes you 3 months if you are lucky, otherwise it never pitches with this incompetency currently in the country. Will a circuit with the 555 work as indicated, I have no problem building circuits😀
Regards
Jan
Regards
Jan
Salvage the speed control from a discarded cordless electric drill? If the rotisserie motor only needs 3V, you'll have to cut one wire to the power MOSFET and run the controller part from a higher voltage. Or use the drill to turn the rotisserie. Either replace the trigger pot with a normal potentiometer, or arrange a lever or screw to press the trigger.
If you're going to DIY, drills could be a source for good power MOSFETs, either in the speed controller or as protection devices in a litihium-ion BMS. Keep in mind that most MOSFETs don't perform well at low gate voltages; most expect at least 10V. Some are made to work at logic levels: their part numbers usually end in an L. (I found an "L" MOSFET in a Dewalt speed control, despite the fact that it used an 18V battery.)
If you're going to DIY, drills could be a source for good power MOSFETs, either in the speed controller or as protection devices in a litihium-ion BMS. Keep in mind that most MOSFETs don't perform well at low gate voltages; most expect at least 10V. Some are made to work at logic levels: their part numbers usually end in an L. (I found an "L" MOSFET in a Dewalt speed control, despite the fact that it used an 18V battery.)
Last edited:
Explanation please
Hi
Just use a LM7805 in front of that transistor . Use a 1Ohm - 5 Ohm Resistor to protect Input of the LM7805. (So the LM7805 will not get hot, no need to use a heat sink) Connect a 10uf/16volt Cap from Pin 1 to Pin 2 and also from Pin 3 to Pin 2. this just to have the Regulator always work. Without you may have dropouts that the Regulator cuts off.
Then use that circuit you have placed. This is far enough and nothing will get hot. I also use this circuit for Fan Control and using a 220 Ohm 2 Watt Resistor from 42 Volts down to 35 for my 12 Volts Regulator.. LM7812, (as LM 7812 can take max 35 Volts) and I never got any problem even with two Fans connected.. Changed the CB "470" to 100 Ohm 1Watt.
Please, now explain me how possible would these 1.5 Volts Batteries allow you to draw 1.78 Amp. these would be gone within 2 minutes. I don't think so.. Clip an DC Amp meter into plus line and measure, or show me a pic of these Batteries. Unbelievable.. Sorry but this sounds strange to me.. Or I'm not up to date about Batteries..
I assume that this motor is 2 Wire? Not a stepping motor. Right? Because Stepping motors would have 2 or 4 wires usually
Did you measure this current or calculate?
All my Amps using FAN with Automatic On Off and Speed Control. And I use a similar Circuit to this one you show.. Never got problems.. Transistor is some BD139, MJE540, 2SD 669 all of them working fine never burned of blew them up. and all without heat sinks.. and transistors are cold.. never hot.
Hope this helps.
Regards Chris
Hi
Just use a LM7805 in front of that transistor . Use a 1Ohm - 5 Ohm Resistor to protect Input of the LM7805. (So the LM7805 will not get hot, no need to use a heat sink) Connect a 10uf/16volt Cap from Pin 1 to Pin 2 and also from Pin 3 to Pin 2. this just to have the Regulator always work. Without you may have dropouts that the Regulator cuts off.
Then use that circuit you have placed. This is far enough and nothing will get hot. I also use this circuit for Fan Control and using a 220 Ohm 2 Watt Resistor from 42 Volts down to 35 for my 12 Volts Regulator.. LM7812, (as LM 7812 can take max 35 Volts) and I never got any problem even with two Fans connected.. Changed the CB "470" to 100 Ohm 1Watt.
Please, now explain me how possible would these 1.5 Volts Batteries allow you to draw 1.78 Amp. these would be gone within 2 minutes. I don't think so.. Clip an DC Amp meter into plus line and measure, or show me a pic of these Batteries. Unbelievable.. Sorry but this sounds strange to me.. Or I'm not up to date about Batteries..
I assume that this motor is 2 Wire? Not a stepping motor. Right? Because Stepping motors would have 2 or 4 wires usually
Did you measure this current or calculate?
All my Amps using FAN with Automatic On Off and Speed Control. And I use a similar Circuit to this one you show.. Never got problems.. Transistor is some BD139, MJE540, 2SD 669 all of them working fine never burned of blew them up. and all without heat sinks.. and transistors are cold.. never hot.
Hope this helps.
Regards Chris
Hallo Chris,
I used a 555 circuit with a mosfet doing the switching. That resistance was measured on the motor itself, that is why I build the power supply, the batteries did not last very long, some of the meat stuff that I make takes a couple of hours to be ready. The circuit works great, thanks guy's !😉🙂
This is what it looks like, build it in a box , I will test it today for the first time,will let you know how it went😀 Deboned stuffed leg of lamb and pork roll.
I used a 555 circuit with a mosfet doing the switching. That resistance was measured on the motor itself, that is why I build the power supply, the batteries did not last very long, some of the meat stuff that I make takes a couple of hours to be ready. The circuit works great, thanks guy's !😉🙂
This is what it looks like, build it in a box , I will test it today for the first time,will let you know how it went😀 Deboned stuffed leg of lamb and pork roll.
Attachments
Last edited:
