Complete Noob probably a silly question! two supplies opposite polarity running DC motor?

Thread Starter

Lucan07

Joined Dec 10, 2016
9
As a builder for many years have a besic knowledge of electrical circuits. As an IT consultant I have a good idea when it comes to coding but currently to relieve boredom while recovering broadening my outlook. Previous experience building PCs, 3d Printer, CNC Router & converting Seig Mini Mill to CNC.

My problem I my vertical blinds to open & close automatically using a photo sensor open when light and close when dark easy with Arduino or Esp8266-01 etc but I think thats overkill.
I have 12v Relays controlled by photo sensor, I have put together a pair of 555 timers Monostable one shot running 3.5 seconds which with 60RPM geared motor gives me required 3.5 turns to close open my vertical blinds, tested individually all works fine.
Now I need to run + & - 5-12v from 2 x 555 timers to a single DC motor safely probably something obvious my old brain missing here so a nudge in the right direction would be handy, keep it simple its either age or the drugs or both but learning seem to get harder as I inch towards retirement!

built a H Bridge with 4x NPN3904 switched voltage fine to Multimeter but dropping to much power when applied to motor.
Motors just the £1 geared Arduino robot toy drives from Ebay plenty of torque & droping voltage not a problem either before or after Timers.
 

MaxHeadRoom

Joined Jul 18, 2013
21,623
What is the purpose of two supplies to run the motor?
Why not simple reversing polarity? Which is what an H bridge generally does.
Max.
 

Thread Starter

Lucan07

Joined Dec 10, 2016
9
A schematic would help?
circuit.jpg
As I say complete new to this plugging kit in and programming it usual method, 12v to relay now common ground & two lives controled by Relay into 555 timers to stop after 3.5 sec leaves me with 2 outputs to attach to single motor with reversed polarity? at which point I had a brain fart!

I may be coming at this from completely wrong direction just trying to avoid Arduino Bluetooth Esp8266 etc want it simple as posssible, my concern is quick switching leaves both circuits open direct short because of 3.5s delay.

thanks for replies as I said completely new to this,
 

blocco a spirale

Joined Jun 18, 2008
1,546
In summary, you need a device that drives a motor in one direction for 3.5 seconds when it gets light, and in the other direction for 3.5 seconds when it gets dark, right?

Whilst I agree that an Arduino (I don't know why you mention a Bluetooth Esp8266?) could be considered overkill, in this instance, because you have coding experience and because H-bridge drivers and light sensor modules are available so cheaply on ebay and they can be plugged together without the need for soldering.... I recommend using an Arduino or a cheaper Arduino clone.
 

Thread Starter

Lucan07

Joined Dec 10, 2016
9
In summary, you need a device that drives a motor in one direction for 3.5 seconds when it gets light, and in the other direction for 3.5 seconds when it gets dark, right?

Whilst I agree that an Arduino (I don't know why you mention a Bluetooth Esp8266?) could be considered overkill, in this instance, because you have coding experience and because H-bridge drivers and light sensor modules are available so cheaply on ebay and they can be plugged together without the need for soldering.... I recommend using an Arduino or a cheaper Arduino clone.
I have Esp8266ex 01 that will easily do job and Arduino pro both cost less than $2 but the requirement is a purely stand alone system light = on/open, dark = off/close, with no programming just plug it in and it works!
 

blocco a spirale

Joined Jun 18, 2008
1,546
I have Esp8266ex 01 that will easily do job and Arduino pro both cost less than $2 but the requirement is a purely stand alone system light = on/open, dark = off/close, with no programming just plug it in and it works!
The problem is your proposed solution and hardware appear to be somewhat convoluted and not ideally suited to the task, and it still needs to be designed, built and wired up. An Arduino is standalone and wouldn't require more than a few lines of simple code to achieve your objective.
 

Thread Starter

Lucan07

Joined Dec 10, 2016
9
The problem is your proposed solution and hardware appear to be somewhat convoluted and not ideally suited to the task, and it still needs to be designed, built and wired up. An Arduino is standalone and wouldn't require more than a few lines of simple code to achieve your objective.
I have it wired very simple but ended with 2 pairs of Live/Neg I need to apply to a motor must be a simple way to do with a 556 or something so only one supply can be live at any time!

Two +- in only one out at any time maybe a diode for protection
 

blocco a spirale

Joined Jun 18, 2008
1,546
I have it wired very simple but ended with 2 pairs of Live/Neg I need to apply to a motor must be a simple way to do with a 556 or something so only one supply can be live at any time!

Two +- in only one out at any time maybe a diode for protection
Ok, but if you pursue this route you must also provide a detailed and accurate schematic of what you have so far.
 

Thread Starter

Lucan07

Joined Dec 10, 2016
9
Where is a link to details of the blue control unit?
Why do you have two 555 circuits?
Max.
Relay just switches between lives so one always live depending on light sensor, one 555 circuit on each live to make it live for only the required 3.5s Ground remains common throughout!
 

BR-549

Joined Sep 22, 2013
4,938
If the ground remains common.....then we can't reverse the motor. We need to flip both ground and power lead to the motor.
 
OK, your blue PCB is the photocell gizmo. I used UP/DOWN rather than open/close and CW/CCW interchangeably.

Generally, you would need an edge trigger (rising and falling) to get your pulses for UP and Down, so you get an 3.5 s UP pulse and a 3.5 s down pulse. Let's assume for the time being, you have that.

There are basically two ways you can control a motor: a) direction/enable and b) cw/ccw signals.

You can use two SPDT relays (one UP/one, one for DOWN). You basically connect the common terminals to each end of the motor, respectively.
The NC terminals on each relay goes to ground. The NO terminals go to +V.

When you activate one relay, you get one direction, the other relay another direction. Activating none or both relays, causes the motor to stop instantly.
 

Thread Starter

Lucan07

Joined Dec 10, 2016
9
OK, your blue PCB is the photocell gizmo. I used UP/DOWN rather than open/close and CW/CCW interchangeably.

Generally, you would need an edge trigger (rising and falling) to get your pulses for UP and Down, so you get an 3.5 s UP pulse and a 3.5 s down pulse. Let's assume for the time being, you have that.

There are basically two ways you can control a motor: a) direction/enable and b) cw/ccw signals.

You can use two SPDT relays (one UP/one, one for DOWN). You basically connect the common terminals to each end of the motor, respectively.
The NC terminals on each relay goes to ground. The NO terminals go to +V.

When you activate one relay, you get one direction, the other relay another direction. Activating none or both relays, causes the motor to stop instantly.
Thats where I started from thinking about two spdt relays but thought that was just a H bridge so would couple of 555s making a H bridge
also be possible, taking original input directly through to H bridge using my two lives& common ground to just switch the H bridge to on & CW/CCW keep size down a little.
 

Thread Starter

Lucan07

Joined Dec 10, 2016
9
it is a little bit puzzling to me how you progressed from a workable / correct solution to an unworkable / incorrect solution.
Everything works to supply currents for correct amount of time I just need to work out how to switch live and common at same time to motor or to use live and common to switch a h Bridge to run motor cw/ccw and turn of when switch off. I have not passed this point, I cannot use Arduino or other control like ESP8266ex 01 Bluetooth etc because it will be in a secure area!
 
I'd suggest to get it to work with two relays first. The relay schematic I described will basically switch the polarity to the motor and use an OPEN and CLOSE signal. It will also BRAKE and not overrun because the motor operates into a short.
 
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