# Speed Controller - Need Help

#### FlashX

Joined Oct 2, 2021
9
Hi guys and girls,

I’m in need of some help and I have a challenge for you.

I am sure this is very simple however I am only a very fresh novice and I have become very confused along the way and need some very clear guidance.

WHAT I'M MAKING

• I am making a marble run using a motor to chain-lift to lift the marbles to the top of the run.
• I am wanting an on-off switch along with a speed controller to regulate the lifting of the marbles in the chain-lift.
• I am wanting to put the components into a large chunk of wood so the cavity is very small and I am unable to use some of the pre-configured boards on the market as generally, the pot is connected directly to the board itself which won’t fit in the wood properly.

WHAT I'VE TRIED

• I have been following the below tutorial:

• I attempted the tutorial and found that the motor was working, however, the pot appeared to not speed up or slow down the rpm.
• I am unsure if I broke a component with heat so I've purchased another set of components to try again.
• I am now aware that it can heat up, so I have also purchased a heatsink.
• Here is a basic schematic I made and it’s what I was working from. Again, I have no idea what I am doing or if it is even correct so please feel free to correct me:

WHAT I NEED HELP WITH

• I need someone to guide me in the right direction, and I would love it if someone could actually draw me up a schematic diagram.
• I’m needing it to be safe to run a few hours at a time.
• I’m hoping I can use some if not all of the components I already have.
• I hoping to make the simplest version possible.

Any guidance and corrections would be very much appreciated.

Thank you for taking the time to help me out.

Cheers,

Jayden

#### LowQCab

Joined Nov 6, 2012
1,317
1)
Don't put the Motor-Controller or Power-Supply, or Switch, inside with the Motor.
The Motor-Diode should be attached directly to the Motor,
and is the only other part installed in the Motor-Box.

2)
Make sure that the Motor has adequate Ventilation, it will get Hot.

3)
The separate Aluminum-Box containing all the Electronics will act as a Heat-Sink,
and provide mounting for the Speed-Control-Pot, and Power-Switch.

4)
Learn the difference between a "Linear-Control", and
a "PWM" (Pulse-Width-Modulation) Control.
PWM is superior in every way.

Are You ready to jump into building a
simple Electronic Circuit on a perforated Project-Board ?
The FET that You have will work as long as it hasn't been damaged by Static.
You will need only a few more specific parts.
.
.
,

#### FlashX

Joined Oct 2, 2021
9
1)
Don't put the Motor-Controller or Power-Supply, or Switch, inside with the Motor.
The Motor-Diode should be attached directly to the Motor,
and is the only other part installed in the Motor-Box.

2)
Make sure that the Motor has adequate Ventilation, it will get Hot.

3)
The separate Aluminum-Box containing all the Electronics will act as a Heat-Sink,
and provide mounting for the Speed-Control-Pot, and Power-Switch.

4)
Learn the difference between a "Linear-Control", and
a "PWM" (Pulse-Width-Modulation) Control.
PWM is superior in every way.

Are You ready to jump into building a
simple Electronic Circuit on a perforated Project-Board ?
The FET that You have will work as long as it hasn't been damaged by Static.
You will need only a few more specific parts.
.
.
,
Thank you so much for your detailed reply, sorry bout not getting back to you sooner, stay at home Dad here and have such little time lol. Is there a PWM board you could recommend? Sorry for asking, I'm just not too confident with this stuff quite yet.

Cheers

#### FlashX

Joined Oct 2, 2021
9
Thank you so much! I'll look into this
Hi again, I've since been looking into 555 timer boards for DC motors, is there any you could recommend with the power adaptor I have? I'm worried I might buy the wrong thing

#### LowQCab

Joined Nov 6, 2012
1,317
A 555, while it will definitely work, and is dirt-cheap,
quite often is not a very elegant solution IMO.
Almost any Dual-Op-Amp can be configured into a precision PWM-FET-Driver
with roughly the same parts-count, and it's hard to get it wrong.

With a PWM Circuit, You probably won't need a Heat-Sink,
but it's good insurance to mount the FET to an Aluminum-Box to dissipate Heat.
If You use a Wood-Box, the Heat-Sink is a good idea.

When I get a spare hour, I'll make You a Schematic and Parts-List.
( I was surprised to find that I didn't already have a simple Schematic ready to go )
.
.
.

#### FlashX

Joined Oct 2, 2021
9
A 555, while it will definitely work, and is dirt-cheap,
quite often is not a very elegant solution IMO.
Almost any Dual-Op-Amp can be configured into a precision PWM-FET-Driver
with roughly the same parts-count, and it's hard to get it wrong.

With a PWM Circuit, You probably won't need a Heat-Sink,
but it's good insurance to mount the FET to an Aluminum-Box to dissipate Heat.
If You use a Wood-Box, the Heat-Sink is a good idea.

When I get a spare hour, I'll make You a Schematic and Parts-List.
( I was surprised to find that I didn't already have a simple Schematic ready to go )
.
.
.
Oh you're awesome! Really appreciate that! I've been tearing my hair out and overthinking everything.

#### LowQCab

Joined Nov 6, 2012
1,317
Here's the DIY version and Part-Numbers from DigiKey.
You can probably get these parts cheaper,
but it adds time and possibly unforeseen complications to the project,
and I don't know how good You are at it.
.
Parts
DigiKey Electronics Part numbers
These are all premium parts, if You shop-around
I'm sure You can find them cheaper,
--------------------------------------------------------------
Capacitors

1- 10nf- 399-C440C103J1G5TA-ND ~$0.45 1- 100nf- C322C104K3G5TA-ND ~$0.88

3- 2.2uf-16V- 478-1868-ND ~$0.68 each 1- 470uf- 16V- 1189-3979-1-ND ~$0.53

-----------------------------------------
Resistors- All- 1/8-Watt - 2%

10- 10k- 2368-EW310-ND ~$0.10 each 5- 2.2k- 2368-EW222-ND ~$0.10 each

5- 1k- 2368-EW210-ND ~$0.10 each ------------------------------------------- High-Speed-Diode C3D02060A-ND ~$1.58

-----------------------------------------

5k-Pot- CT3051-ND ~$4.10 --------------------------------------- 1- Perf-Board- 1988-1000-ND ~$5.oo

-----------------------------------------

1- 8-Pin-DIP-Socket- 2368-NTE423-ND ~0.46

----------------------------------------------

1- Dual-Op-Amp LM6142BIN/NOPB-ND ~$5.oo . Last edited: #### zophas Joined Jul 16, 2021 155 @LowQCab Part number for the MOSFET, please. I am also interested in this. Thanks for posting it. #### LowQCab Joined Nov 6, 2012 1,317 You didn't provide your Motor Specs. The MOSFET depends on the Current and Voltage of your Motor. For small ~12-Volt Motors like the one here, You can use almost any FET, but I prefer ridiculously over-rated parts personally, there's less chance of letting-out the Magic-Blue-Smoke. . . . #### click_here Joined Sep 22, 2020 446 You didn't provide your Motor Specs. I found it on the original parts list, but I couldn't find a stall current 12V DC 10RPM Powerful High Torque Gear Box Motor: https://www.ebay.com.au/itm/330737369534 It might pay to do some measurements with a multimeter, or contact the supplier. Also, note that the tantalum capacitors are usually polarised, but it should be easy to see which side is '+' from LowQ's schematic. Ask if you're not sure #### LowQCab Joined Nov 6, 2012 1,317 I made a serious mistake in the Schematic. A revised version will be up soon. . . . #### LowQCab Joined Nov 6, 2012 1,317 Schematic corrected. 1 Resistor out of place. . . . Thread Starter #### FlashX Joined Oct 2, 2021 9 No Here's the DIY version and Part-Numbers from DigiKey. You can probably get these parts cheaper, but it adds time and possibly unforeseen complications to the project, and I don't know how good You are at it. . Parts DigiKey Electronics Part numbers These are all premium parts, if You shop-around I'm sure You can find them cheaper, Your mileage may vary. -------------------------------------------------------------- Capacitors 1- 10nf- 399-C440C103J1G5TA-ND ~$0.45

1- 100nf- C322C104K3G5TA-ND ~$0.88 3- 2.2uf-16V- 478-1868-ND ~$0.68 each

1- 470uf- 16V- 1189-3979-1-ND ~$0.53 ----------------------------------------- Resistors- All- 1/8-Watt - 2% 10- 10k- 2368-EW310-ND ~$0.10 each

5- 2.2k- 2368-EW222-ND ~$0.10 each 5- 1k- 2368-EW210-ND ~$0.10 each

-------------------------------------------

High-Speed-Diode C3D02060A-ND ~$1.58 ----------------------------------------- 5k-Pot- CT3051-ND ~$4.10

---------------------------------------

1- Perf-Board- 1988-1000-ND ~$5.oo ----------------------------------------- 1- 8-Pin-DIP-Socket- 2368-NTE423-ND ~0.46 ---------------------------------------------- 1- Dual-Op-Amp LM6142BIN/NOPB-ND ~$5.oo

.
View attachment 249590
Thank you so much! That's a wonderful help and I hope it can help others too!!

#### FlashX

Joined Oct 2, 2021
9
Schematic corrected.
1 Resistor out of place.
.
.
.
Haha! Thank you