Need help to create safety device which will stop window blind going down if something is in the way

[Mindaugas]

Nice work mate finally moving forward were do you live ? if UK I will try organize stay in our 5 star hotel at shard can not guarantee but possible now I need to try this thing out to be honest don't understand witch parts to get but I will analyse it all next week I am of work

 

[Mindaugas]

don't understand meaning of q1 and c1 c2 c3 c4 is C stands for capacitor ? picaxe-08m will order now with LM78L05

 

[KMoffett]

I live in Minnesota, USA. Probably won't show up there soon. Q1 is a MOSFET transistor. Yes, C is for capacitor. I get that you have little electronics experience. The PICAXE requires programs to be developed and installed. Maybe you can find an electronics hobbyist in you area to build you a prototype.

Ken

 

[Mindaugas]

Ok, I still think it must by easy way to do it mate. Motor has 4 cables for control and 2 for power. Control common is ground and up down and stop is 24v dc pulse signal. If we use pulse relay to switch normal power supply for motor on and off. When connect motor constantly with power supply in series with current limiting diode or other component on witch I need help from you

 

[KMoffett]

Now you've add another cable with control signals to the equation...and constant power to the blind. Is there anything else in the "actual" system of these blinds?

Will cutting power to the blind reset the blind to STOP? That would simplify my circuit in that I don't need to compensate for reversing UP and DOWN power polarity. If so, I'll revise my circuit for that.

"When connect motor constantly with power supply in series with current limiting diode or other component on witch I need help from you"
Now that's just pulling words out of thin air. Are you fixed on a one component solution? I doubt that's going to happen. Also, I will bet that current levels will vary from blind to blind, and as they age. That's why I add the ability the adjust the trip levels.

Ken

 

[KMoffett]

In trying to deal with things I don't know, you implied the there the limits on the blind deployment was time. Are you sure of that?

Ken

 

[Mindaugas]

its constant 24v dc power and 4 core cable for control witch is, Common, up, down, and stop. I was trying to test voltage on control cable, but its volt free. I think its negative from power supply connected to common . Well to be able to adjust current its much better but I was thinking that it must Be one perfect current trip level for all blinds because all of them when going down are affected by weight of bottom bar and material. and its easy for me just to add weight to blind to reduce current if blind is very light. Its getting to complicated in beginning it looked simple. I see why is no 24v dc motor with protection like that one the market but I need to try.

 

[Mindaugas]

yes because if power is down for blind you can change limit by forcing motor down and limit will change

 

[KMoffett]

"yes because if power is down for blind you can change limit by forcing motor down and limit will change"

I don't understand this.

Ken

 

[Mindaugas]

Well I know just 2 ways for motor to have positions. One is o-10 volt control, another is by time. Rise lower and for 0-10 volt controlled motor you can manually spin motor with power disconnected and it will have same limits, but for time controlled motor if you do this limits will change

 

[KMoffett]

So there are ones installed with different controls...0-10V and UP/Stop/Down?

Ken

 

[Mindaugas]

No, it's works on time mate. Sorry for not making my self clear. English is not my first language and thaks a lot for helping me

 

[KMoffett]

OK back to my question: if you cut power to the blind as it's moving down and then reconnect the power, does it revert to Stop?

Ken

 

[Mindaugas]

yes it dose

 

[KMoffett]

Here is my latest iteration. Once the currents drops to within a selected range (less that DOWN and more than STOP), the relay opens and kills power to the blind. The relay then closes and waits for outside intervention to lift the blind. Noticed I didn't put in any component values. This would have to be prototyped with actual blinds.



Ken

 

[Mindaugas]

Looking good just need to get it done I am abit scared of programming chip but I done some c++ it must be close to it

 

[KMoffett]

The PICAXE microcontrollers are programmed in BASIC. To familiarize yourself with the chip and programming software (free) go to http://www.picaxe.com/
"...just need to get it done" Is there a time crunch? Have you promised someone this control with "That should be simple!"

Ken

 

[Mindaugas]

No mate, but I love solving problems. For this one I spend a lot of time and is cool project if it's works will save a lot of problems for us

 

[Mindaugas]

Ken This micro controllers is very cool I was just thinking, can this micro controler give 0 v to blind stop cable on control side instead of using relay and q transistor ?

 

[KMoffett]

If the ground on the Up/Stop/Down cable is also connected to the negative of the motor supply, then yes. If not, and opto-coupler could be used. I was trying to stay away from getting into both cables.

Ken