Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

very basic question

Status
Not open for further replies.

Catattafish

New Member
Hi Guys,

I am new to these forums and really inexperienced in circuit design. I have had some electric and electonics training but that was years ago and limited.

Here is my project. I would like to add 3 LED's to a model tank, and have the radar array rotate, powered by a 9v battery.

The three LED's voltage are

4.5 v white
4.5 v white
2.2 v blue

The motor is a mini DC motor taken out of a remote control servo. I have retained the gear box to slow the output speed down.


I plan on wiring the led's parallel, and using 3 separate resistors to ensure that each one lights up. (this I can figure out)

The problem is, is that 9v is way too much for this little motor, it is way too fast and gets hot quickly. When I power the motor with a AA 1.5, the speed is perfect and it does not get hot. I really have two questions.

1) Is there an electronic device that will slow the motor down even feeding it 9v parallel? or even slower that I can remove the gear box (it's bulky for my project)

I have read about resistors and that they may overheat and will drain the battery and also very little on potentiameters which I don't know if I have room?

If there is a device, can you point me to a website where I can purchase?

Or can I wire the LED circuit in series with the motor? How will that affect the overall draw on the battery and motor speed.

Thank you everyone in advance for looking at this question. I would appreciate if you can "dumb" down your answers ;)

Cat/
 
Last edited:

namezero111111

New Member
Well, you could try to use an adjustable voltage regulator such as the LM317T which can be regulated down to 1.2V, as long as the motor doesn't draw more than 1.5A, which I doubt it would.
The good thing about this part is that it is versatile and available at your local RadioShack.

Find more info on this chip here:
https://www.national.com/mpf/LM/LM317.html
 
Last edited:

Catattafish

New Member
I will certainly check that out, I think that will work just fine! The motor in the servo (including the gearbox) worked best at 1.5 v (AA). However, when I take out the gearbox and run it at 1.5 it is way to fast. I love the size benefit of removing the gear box, but if this voltage regulator works, that's awesome too.

Thank you so much for helping me, I will let you know how I make out.

Cat/
 

kchriste

New Member
Forum Supporter
You could go the other way and use only a 1.5V battery. Then use a joule thief to light the LEDs.
Or for if you want it really simple use a 1.5V and 9V battery for the motor and LEDs respectively.
 

Catattafish

New Member
Hmmmm,

I will read up on the Joule thief!, I have though about the two different batteries but I am limited by space, so I would much rather stick to one. Thanks so much for your reply, gunna go read on the thief!

Cat
 

Catattafish

New Member
Hey Guys,

Here is what I have come up with. (I have no specs on the motor, it was taken out of a Remote control servo and appears to run fine and cool on 1.5 v with correct speed)

Can you please give me your opinion if this any errors on my schematic or if something needs to be corrected?

[/URL][/img]

Any guesses on the length of time this 9v will last? sorry I don't have the draw of the mini servo motor!

Cat/
 

colin55

Well-Known Member
You need this very clever motor speed controller:
8583-MotorSpeedController.gif


It adjusts the current through the motor so it has a high start-up torque. It's a switch-mode circuit.
 
Status
Not open for further replies.

Latest threads

EE World Online Articles

Loading
Top