The L293N on the board with ready made interface may prove a little less trouble?

I already have that one (came yesterday) but the size is not going to work on my project and that is why I was looking at the L293N asi can make the circuit smaller…?

 

I already have that one (came yesterday) but the size is not going to work on my project and that is why I was looking at the L293N asi can make the circuit smaller…?

I think you will need a transistor H Bridge or a transistor/mosfet arrangement if the control signal is only 2 volts.

 

I think you will need a transistor H Bridge or a transistor/mosfet arrangement if the control signal is only 2 volts.

Thank you for your reply and yes I know I will need a transistor to switch thee 2 volt signal. I’m think of using BC558 transistor as my increased trigger source?

Thank you, Ron

 

One suggestion, depending on how the 2 volt trigger is generated.
What is the source of this trigger pulse?

 

Whatever device is used to drive the motor will need to have both sides able to provide both a current SOURCE mode AND a current SINK mode, with both modes being adequate to supply the requred current. An open collector output will not be able to do that directly.

 

An open collector output will not be able to do that directly.

Are you referring to my circuit in post #24?

 

The NE555 can Sink or Source 200ma !

 

Hi guys, I have looked into the l293n and the l293d, but just realized that the voltage drop in them is too much for me and will make the motor run too slow.

i am now thinking of making a mosfet h-bridge to cut down on voltage loss. I came across this circuit and was wondering if this would be a good start to my project and wanted to get you guys opinions on it.

I tried sending it as a file but to would not let me so I took a pic of it to give you an idea on what Im thing of using.

thank you, Ron

 

Technically it looks correct using switches but where does this 2 volt trigger pulse work in the circuit?

 

Thank you for your reply MaxHeadRoom, will that module run my 12vdc .02amp motor at full speed? That is one of my big concerns.

thank you Ron

 

Technically it looks correct using switches but where does this 2 volt trigger pulse work in the circuit?

The two volt signal come from a out side source that only comes on for about 3 seconds then off.

thank you, Ron

 

Technically it looks correct using switches but where does this 2 volt trigger pulse work in the circuit?

The switches will be replaced with separate external sources

 

The switches will be replaced with separate external sources

Suggestion using a single 2 volt trigger.

 

Suggestion using a single 2 volt trigger.
View attachment 368948


Thank you sghioto, can you expand on this circuit a little for me. I see that it has a 2v trigger but I do not understand where the second trigger is. I want to operate this switch as two position, forward and reverse.

I’m very interested in this circuit, it is small and uses small housed MOSFETs keeping the foot print small and low cost.

On another note the second trigger will be a 12vdc pulse, so one direction with a 2 volt signal and the other direction with a 12volt signel.

Thank you, Ron

 

Originally it was stated that the 2 volt pulse ran the motor forward and in reverse when removed which is what this circuit does.
What should be the state of the motor if neither pulse is active or if both pulses are active at the same time, or will that not be an issue?
I'll draw it up using both the 2volt and the 12volt pulse later today.

 

Originally it was stated that the 2 volt pulse ran the motor forward and in reverse when removed which is what this circuit does.
What should be the state of the motor if neither pulse is active or if both pulses are active at the same time, or will that not be an issue?
I'll draw it up using both the 2volt and the 12volt pulse later today.

Hi sghioto, sorry for the confession and want to thank you for your help and ideas.

Ok, let me clear things up. I need a nice smaller circuit using mosfets to switch to control a 12vdc motor @20ma forward and backwards. One direction is controlled by a 2vdc source and the other direction with a 12vdc p for 1/2 second and and quite. The motor is off until the next 2volt signal for approximately 3 to 5 seconds. The power goes away it starts the timer 12vdc pulse to the other direction for 1/2 second.

I like the circuit with the mosfets you showed, it need to be controlled with the 2volt for one direction and 12 volts for the other direction.

If anyone is interested on what this is used for, it is a way to use the (3D printing) Bambu AMS-lite so I can use my own feeder boxes and replace the problematic mechanical retract system. I can supply more details if anyone wants to know more about this project?

Thank you, Ron

 

I like the circuit with the mosfets you showed, it need to be controlled with the 2volt for one direction and 12 volts for the other direction.

One version:
With pulses not active the motor is OFF.
2V pulse turns ON Q5,Q3,Q6 and Q2. Motor runs from B to A.
12V pulse turns ON Q7,Q4, and Q1. Motor runs from A to B.

 

Why do we have to play guessing games about the details of questions like this? First it's a circuit designed to make a motor run one way in the absence of a 2V pulse and reverse when the pulse is there; no 'off' position is required. Then we find that there IS an 'off' position, and the motor only runs in reverse for a short while, then switches off. Now a mysterious 12V pulse has appeared, causing further confusion.

As a party game at Christmas, this might be quite fun; as a serious attempt to get a solution to a technical problem, it's a mess. Why not just tell us exactly what the device is/does, and it might make for better solutions – and less work for your helpers!

 

One suggestion, depending on how the 2 volt trigger is generated.
What is the source of this trigger pulse?
View attachment 368935

Nice approach. Just adding a thought; a 556 (dual 555) can do the same thing. maybe take up a little less real-estate on the board.

The H bridge looks good too.

 

Nice approach. Just adding a thought; a 556 (dual 555) can do the same thing. maybe take up a little less real-estate on the board.

The H bridge looks good too.

Thanks.
The concern is the voltage loss on the outputs hence using the discrete H bridge.