Working With A DC Motor.

To sum it up, I have a circuit with transistors that are used for a password lock and a self made 3 position see-saw switch with 4 buttons to turn a motor both directions. I have been told you need a diode on the motor, but my motor turns both ways. Instead of a diode, could I use a capacitor like the 104? Apparently I need to stop some "Inductive Kickback" or something like that because it will damage my transistors, so what should I do if the motor turns both ways? Thanks.

Hi,
A 0.1uF cap would help with EMC noise from the brushes.
Can you post a circuit showing your motor control circuit, and we can then suggest the alternatives..

Thanks.. Tom... :slight_smile:

You need not one but four diodes for this.
See reply #6

Apparently I need to stop some "Inductive Kickback" or somethin

See

Accept I am not using an H bridge.

Hi,
Can you post a circuit showing your motor control circuit, and we can then suggest the alternatives..

Tom... :slight_smile:

Then WTF are you using?
What a super unhelpful reply.

I suspect you are but don’t realise it.

It doesn’t matter because you still need four diodes.

From your signature

I sincerely appreciate everything you say, and all the time that you spend helping me.

It doesn’t sound like it. Try and live up to this and cooperate.

Rapid80:
To sum it up, I have a circuit with transistors that are used for a password lock and a self made 3 position see-saw switch with 4 buttons to turn a motor both directions. I have been told you need a diode on the motor, but my motor turns both ways. Instead of a diode, could I use a capacitor like the 104? Apparently I need to stop some "Inductive Kickback" or something like that because it will damage my transistors, so what should I do if the motor turns both ways? Thanks.

If the motor is supposed to work in both directions you require an H-bridge, which is a set of 4 switches or
switching devices with a diode across each one.

Perhaps you should post the circuit you actually have to avoid confusion.

Rapid80:
To sum it up, I have a circuit with transistors that are used for a password lock and a self made 3 position see-saw switch with 4 buttons to turn a motor both directions.

To possibly interpret;
Self made== DIY
3 pos see-saw == a rocking mechanism.
4 buttons == 4 momentary NO switches that are positioned under the see-saw.
See-Saw in its middle position, no buttons pressed.
See-Saw in one position, 2 buttons pressed under it, connecting motor in one direction polarity to power supply.
See-Saw in second position, the other 2 buttons pressed under it, connecting motor in other direction polarity to power supply.
How the See-Saw is moved, my crystal ball didn't say.

We need a picture of your project please?
Tom.... :slight_smile:

Hello. In his last reply, Tom got it perfect. You press the see-saw switch manually, and the switch controls two buttons on either side. Also, I had to get off of my computer and immediately started designing the circuit at school. I am still on mobile currently and will try to send a hand-drawn circuit asap. I didn't realise that I was being uncooperative and unclear, so I will try to work on that. Also, I do appreciate every reply, so by learning I wasn't being helpful, now I know to work on that for my future posts. I had to go to school, so I didn't get a chance to post much. Thanks.

Sorry for the sloppiness.

EDIT: The picture won't upload so I will try on my computer in a little bit.

How did you try to upload the photo ?
Post a screenshot of the error you got .

Are able to upload any photos at all ?
(you could draw the schematic , photograph it and post it)

because it will damage my transistors

What transistors?

Basicly the transistors are part of a “password” lock used to control the motor. All are NPN, and it consists of a not gate with an and gate and finally a power transistor. I will post both circuits. “R1” and “R7” are the password switches.

2020-03-02.jpg

4 buttons is 4 switches, so 4 diodes across them. Its an H-bridge.

The motor can only turn one direction with that circuit,

AND the npn transistor is backwards. The emitter needs to go to ground and the collector
needs to connect to the motor.

That's Transistors-101

I think you may have only looked at the password circuit, because the four switches can make it go both ways.

And with the circuit below (which is basically what I drew), can someone tell me exactly wear to place the 4 diodes? I am just confused with how the whole diode system works. Thanks.

unnamed.png

Diode across every switch, cathode towards +ve supply. Thus when a switch opens the current can continue to flow through the diode without arcing the switch and welding it shut. Inductive currents cannot be turned off instantly, the inductor will generate whatever voltage is necessary to prevent this.

Question: Wont the diodes decrease the voltage by 1.4 because of the .7 volt drop if I use regular diodes? Also, would this be an accurate schematic with the 4 momentary buttons?:

4iGc7.png

No.
Google H-bridge.
The current flows through the motor.
The diode are there as flyback (backemf)
protection.