Greetings,

I am currently building an IR remote control system to control the speed of a motor. I was told that I should install a few bypass capacitors to cut down on noise. However, I am unsure of how to determine the placement and value of the capacitor. I don't want to mess up the timing of my 555 timers.
Here's the circuit schematic I'm using:

Here's the specs for the motor I'm using:
Torque: 0.1 Nm
Total Power: 11 Watts
Maximum Current: 2.44 A

I appreciate any feedback! Thanks

 

The bypass capacitor(s) go between the power and ground pins and as close to the device as practical. They will not mess up the timing.

John

 

Thanks for the quick reply! So to clarify, the capacitor should be in parallel to the motor?
Also what size do you think I should use?

 

Thanks for the quick reply! So to clarify, the capacitor should be in parallel to the motor?
Also what size do you think I should use?

I think that the capacitors should be inserted between the supplies and ground pins of each ic.

Please see attached pic. Can't remember where I got it from anymore though. Apologies to the author...

 

I think that the capacitors should be inserted between the supplies and ground pins of each ic.

Please see attached pic. Can't remember where I got it from anymore though. Apologies to the author...

Oh and as Jpanhalt said, as close to the chips as possible. Normal ceramic discs should do.
Max

 

http://forum.allaboutcircuits.com/threads/decoupling-or-bypass-capacitors-why.45583/

 

There's a difference between adding bypass (or decoupling) capacitors to your ICs and connecting a capacitor in parallel with your motor, and they serve different purposes.
Dave Jones did an excellent job explaining bypass capacitors in this video.
If you want to cut down on the noise caused by a (brushed) DC motor, you could add a capacitor in parallel to it, but since you are using PWM (Pulse Width Modulation) to control the speed, this won't help in your case, and it might help to add larger (electrolytic) capacitors across the power rails, close to the motor driver. Read more here: http://robotics.stackexchange.com/a/272

Pieter

 

I appreciate all the advice and resources that have been shared! There is definitely a lot more involved in circuit design than I originally thought. One question that I still have is testing my design. I don't currently have an oscilloscope and I can't afford one at the moment. Are there any alternatives, such as using a simulator, that I can use?

 

Greetings,

I am currently building an IR remote control system to control the speed of a motor. I was told that I should install a few bypass capacitors to cut down on noise. However, I am unsure of how to determine the placement and value of the capacitor. I don't want to mess up the timing of my 555 timers.
Here's the circuit schematic I'm using:

Here's the specs for the motor I'm using:
Torque: 0.1 Nm
Total Power: 11 Watts
Maximum Current: 2.44 A

The LM555's are kind of noisy.
Here is what the datasheet calls for.

 

Thanks a lot @ronv for pointing that out!
Personally, do you have any recommendations of 555 timers? Or do they all produce quite a bit of noise?

 

Thanks a lot @ronv for pointing that out!
Personally, do you have any recommendations of 555 timers? Or do they all produce quite a bit of noise?

The CMOS version (LMC555) is quieter, but can't drive as much current.

 

okay, that might actually work better. I'm going to be running this system with a 4.5 V battery source.
I'll check out its data sheet

 

Thought I would let you guys know about autodesk circuits. I am planning to use it to work out some of my schematics.
Does anyone have any other suggestions for simulating circuits?

Thanks