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Old 09-25-2015, 06:08 AM   #21 (permalink)
 
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Default Re: Custom electronic device with PCB?

Quote:
Originally Posted by i2D__ View Post
This looks like what I was looking for and I have maplins round the corner from me, only thing to add to this is if its possible to flip the switch and when the blind reaches the top it stops the motor. This is why I thought i'd need a PCB board to program the motor to stop after a certain distance (time) ?
for distance. You'll need either a micro switch, (so that there is a switch pressed when the thing gets to the top/bottom, or on of those light gate things...
and a couple of diodes

(i'd probably go with the switch since the come with a nice big lever that can be hit anywhere along the bar to stop the bind, whilst if you go for a light sensor based one you need to make sure your flag if lined up properly to go into the slot, if a little breeze means that the flag doesn't go into the hole properly, then you can keep your blind going.)

essentially, you have the switch set inline with the circuit, so that it's normally closed state will let power run in any direction. and then you have the diode bridging the switch so that when it get's to the top. the switch contacts break apart, and the diode is also blocking the flow of current to let the motor wind up any more.

But when you press down, whilst the switch contacts are still broken and won't allow current to flow, the diode will allow current to flow, (but only letting the motor spin in the down direction). that way you wind down with current going through the diode, the micro switch resets and then current will pass through the switch letting you do either up or down once again.


I'll draw out the circuit diagram when I get home, (or sometime over the weekend) so you know what connections go where.



if you want it done as a function of time, (i,e I press a button and it winds for three seconds only, press again and it'll wind for three seconds.
then you'll need a timer. (and a relay since there is a limit to the amount of current the chip you use could either source or sink.)

this can either be done using a 555 one shot timer, (otherwise known as a monostable multivibrator) or using a microchip (Ardiuno (if you want the whole devboard) Atmel, PIC etc for just the chip.) - I'd recommend the 555 approach, not least because it is simple, but it's the most useful in terms of learning...

(t = 1/rc) to set the time - i.e you just replace a resistor or capacitor to change the time the circuit stays on for.

or you have to go back to your source code/sketch
change the bit that says :
portb = 1; //set motor on
delay_ms(3000); // wait 3 seconds
portb=0; //turn motor off

then recompile and upload the new firmware (which may involve taking the thing apart, if you're done it with an IC instead of a DEV board then you may have to unsolder the chip (unless you used a chip socket)


Whichever you choose both timer approaches will require a PCB,
Just putting the micro switches inline and diodes across them can be done without a circuit board. (but obviously it's not as cool as pressing a button and walking away.)
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Old 09-25-2015, 06:09 PM   #22 (permalink)
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Default Re: Custom electronic device with PCB?

Quote:
Originally Posted by -root- View Post
for distance. You'll need either a micro switch, (so that there is a switch pressed when the thing gets to the top/bottom, or on of those light gate things...
and a couple of diodes

(i'd probably go with the switch since the come with a nice big lever that can be hit anywhere along the bar to stop the bind, whilst if you go for a light sensor based one you need to make sure your flag if lined up properly to go into the slot, if a little breeze means that the flag doesn't go into the hole properly, then you can keep your blind going.)

essentially, you have the switch set inline with the circuit, so that it's normally closed state will let power run in any direction. and then you have the diode bridging the switch so that when it get's to the top. the switch contacts break apart, and the diode is also blocking the flow of current to let the motor wind up any more.

But when you press down, whilst the switch contacts are still broken and won't allow current to flow, the diode will allow current to flow, (but only letting the motor spin in the down direction). that way you wind down with current going through the diode, the micro switch resets and then current will pass through the switch letting you do either up or down once again.


I'll draw out the circuit diagram when I get home, (or sometime over the weekend) so you know what connections go where.



if you want it done as a function of time, (i,e I press a button and it winds for three seconds only, press again and it'll wind for three seconds.
then you'll need a timer. (and a relay since there is a limit to the amount of current the chip you use could either source or sink.)

this can either be done using a 555 one shot timer, (otherwise known as a monostable multivibrator) or using a microchip (Ardiuno (if you want the whole devboard) Atmel, PIC etc for just the chip.) - I'd recommend the 555 approach, not least because it is simple, but it's the most useful in terms of learning...

(t = 1/rc) to set the time - i.e you just replace a resistor or capacitor to change the time the circuit stays on for.

or you have to go back to your source code/sketch
change the bit that says :
portb = 1; //set motor on
delay_ms(3000); // wait 3 seconds
portb=0; //turn motor off

then recompile and upload the new firmware (which may involve taking the thing apart, if you're done it with an IC instead of a DEV board then you may have to unsolder the chip (unless you used a chip socket)


Whichever you choose both timer approaches will require a PCB,
Just putting the micro switches inline and diodes across them can be done without a circuit board. (but obviously it's not as cool as pressing a button and walking away.)
To you this may be the most simple set up, but you blow me away! lol Im finding it hard to understand the technical set up but understand the end result is what i want I think the diode is a better option than a timer as I want a simple setup.

I'm going maplin (UK store) tomorrow, please let me know what I need to pick up besides the switch and motor, are all diodes the same?
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Old 09-25-2015, 06:49 PM   #23 (permalink)
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Default Re: Custom electronic device with PCB?

Nope they aren't, what power source are you using again? Something like this should work regardless of what you choose though: http://www.maplin.co.uk/p/1n4004s-1a...ectifier-ql76h
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Old 09-26-2015, 05:53 AM   #24 (permalink)
 
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Default Re: Custom electronic device with PCB?

I guess your parts list is going to be something like this for the motor:
MFA 12-24V Small 100:1 Single Ratio Motor Gearbox | Maplin
(you want 1)
Assuming you run it from the lowest voltage 6v then the 1.3W motor will draw 0.21A (I only used the lowest voltage as that would figure the highest current draw).



so really you want a 1 amp or greater diode.

1N4004S 1A Silicon Rectifier | Maplin
(you want 2, one for top and one for bottom)

for the micro switches, depending on how confident you are the blind will rise and fall at the same position (and not move in a breeze)

you either want this one:
Low Cost Standard Microswitch with Lever | Maplin

or one with a bigger level that allows the blind to get to the bottom, but in a less specific place
V3 Style Alarm Tamper Switch | Maplin

(you'll want two, one for top one for bottom)


after that you'll want a battery box.

I've not seen the blind, so I don't know how fast you want it to turn...
so the battery box will depend on the voltage that you want to put onto the motor.
(and there is a chart as to how fast the motor will turn for a given voltage on the motor page.)

Then you'll want some wire to hook it all up with. and a switch. soldering iron and solder...
When you buy the soldering iron don't get the 25w one, they are essentially just terrible to use, get a 30 or 35w one.


When you're putting it all together you'll want an old wooden chopping board out fo the kitchen to lean on to save you burning holes in your desk etc.
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Old 09-26-2015, 06:38 AM   #25 (permalink)
 
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Default Re: Custom electronic device with PCB?

Quote:
Originally Posted by i2D__ View Post
To you this may be the most simple set up, but you blow me away! lol Im finding it hard to understand the technical set up but understand the end result is what i want
That's understandable, it's easy to get carried away with something... I'll draw some pictures to help you understand a little better.

Ok, this is the circuit.


unfortunately I don't have a 2pole 2throw with center off switch in my software, so you'll just have to imagine that the switch right next to the battery is not there any actually the center position of the switch that looks a lot more complicated.

so at this point the blind is all the way to the top. it's hit that top microswitch and the switch is open.

so now you move your switch to the go up position:


and nothing happens?
why? because the switch is open, so there is no path for the current to flow there, and the diode blocks the current, so there is no current to flow there.

put the switch in the down position, and the blind move down, with current flowing through the micro switch at the bottom and through the diode at the top.



also the top micro switch no longer is held open by the blind so that springs closed. (now the current could flow either direction through the switches.


Now the blind reaches the bottom, so the bottom switch opens. at the top half, current could flow to move the motor in the downward direction through either the the microswitch or the diode.
at the bottom the diode blocks the current, and now that there is a blind sitting on the switch at the bottom holding it open, no current flows through that.



put your movement switch in the up position, and the blind will go up (with current flowing through the switch at the top and diode at the bottom.



As before, with the blind not holding the switch the switch will close.

so in this picture, both switches are closed (the blind is in the middle) and the up down switch is in the middle (off) position.



so now it can go up, or down. with current flowing through the switch in either scenario




does that make more sense?


Quote:
I'm going maplin (UK store) tomorrow, please let me know what I need to pick up besides the switch and motor, are all diodes the same?
the motor I linked to is a web only deal, that's probably not as bad as you think as it'll let you slow down a bit and understand what's happening!

Have you figured out the mounting and how you're connecting it all the motor to the string that works the blinds? (or are you attaching directly to the roller?)
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Old 09-26-2015, 09:30 AM   #26 (permalink)
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Default Re: Custom electronic device with PCB?

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Originally Posted by -root- View Post
does that make more sense?



the motor I linked to is a web only deal, that's probably not as bad as you think as it'll let you slow down a bit and understand what's happening!

Have you figured out the mounting and how you're connecting it all the motor to the string that works the blinds? (or are you attaching directly to the roller?)
It does make sense, but hard to visualize - but I get the process.

I was thinking of having the motor next to the roller and hooking a band on the roller itself so it winds it down. so I can mount the motor behind the roller and all I'll see is the blind going down/up. Ill taken pics of the items, Ill see if they have the motor in store (even if its more money)
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