This picture should be more clear.
Al.
Edit: picture is too small to see details, I attach a zipped one
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This picture should be more clear.
Al.
Edit: picture is too small to see details, I attach a zipped one
Last edited by aratti; - 26th June 2009 at 07:13.
All progress began with an idea
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Have you ever tested or used your circuit with a latching
aratti,
Thanks for the schematic. Yours is a better approach than mine because it only requires two SPDT relays instead of two DPDT relays...cheaper! However I am a little concerned about whether "nothing happens" in your circuit for the state where both Relay 1 and 2 coils are turned on and both the Red and Black wires are connected to +9vdc. I am not certain what the latching solenoid does that I am looking at when both wires are high.
Have your ever tested or used your circuit with an actual latching solenoid? If so what was your experience and can you refer me to the Part No. for the one you used??
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Latching solenoid are just a normal solenoid with the addition of a permanent magnet. When you connect the coil (Red to + and Black to 0) the magnetic field attract the iron core and when the core is in contact with the permanet magnet it will be hold without the need of the magnetic field generated by the coil. So to activate it you just keep the coil connected for a very short while.
If you need to de-activate the solenoid, you will need to generate in the core a reverse magnectic field so that the core will be pushed away from the permanet magnet holding it. To obtain such a result you simply reverse the current flow into the coil, connecting the Red to 0 and the Black to + and hoops the solenoid has released the core.
If you connect both wire to zero volts or both wire to +9 volts nothing will happen, and when I say nothing I mean it (no current will circulate at all), and the solenoid will keep is position. This is the max I can say to assure you.
Have a nice day.
Al.
Last edited by aratti; - 26th June 2009 at 08:32.
All progress began with an idea
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Instead of putting the battery terminals on the common of the relay, put the solenoid terminals on the common pins, and use a DPDT relay. Wire the N.O. pins with power and ground and wire the N.C. terminals opposite of the N.O. ones. With a DPDT relay you only need one control pin also.
Tim Barr
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Will this schematic work like yours?
Anrati, I have designed the Relay Circuit for use with my 16F690 MCU as shown in the attached partial schematic. As you can see, pin RC2 controls one of the two SPDT relays and pin RC3 controls the other. I have purposely wired the ground from the battery rather than the positive terminal to the normally closed contacts on the two relays so that in case there is any leakage in the Solenoid_RED or Solenoid_BLACK wire circuits it won't drain the battery when the relays aren't actuated.Originally Posted by aratti
Do you think this circuit will work? One of my concerns is finding a SPDT relay that can be operated within the 25 mA limit of the MCU output pin. Any suggestions where I can get one?
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Hi John,
Why not just use an H Bridge to control your solenoid ?
If you do not believe in MAGIC, Consider how currency has value simply by printing it, and is then traded for real assets.
.
Gold is the money of kings, silver is the money of gentlemen, barter is the money of peasants - but debt is the money of slaves
.
There simply is no "Happy Spam" If you do it you will disappear from this forum.
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Yes.Do you think this circuit will work?
See at this link they have reed relay @ 5V 10 mA.One of my concerns is finding a SPDT relay that can be operated within the 25 mA limit of the MCU output pin. Any suggestions where I can get one
http://www.americanrelays.com/dip.pdf
Al.
All progress began with an idea
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When I need a strange combination of logic gates that doesn't have to be exceedingly fast, I usually use a small PIC (12F series for example). Small, cheap and can be programmed to any function I need. The best part is that if I want to change something later, I can do it with programming instead of X-acto knives and little blue wires.
Charles Linquist
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h-bridge
L293d
tle 5205-2
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Right drive current...wrong drive voltage..any others?
My 16F690 MCU is operating at 3.3 vdc. Therefore I need a relay (SPST or SPDT) whose coil voltage is 3.3 vdc with a coil resistance of 132 ohms or more, and a contact rating for 1 Amp when switching and 0.5 Amps when closed:
3.3 vdc/.025 ma = 132 ohms
Do you know of any sources? I have looked high and low with no success...most have coil resistances that require drive of 50 mA or more which is above 1-pin drive capabilty of the 16F690 and I didn't want to have to use more than one pin to trigger the relay.
I have read that many of the 5V reed relays will still operate at 3.3vdc. What do you know about this?
I appreciate your help. I am going to investigate the suggestion to use an "H-Bridge", but I know nothing about them. Can you point me to any good tutorials on H-Bridges for controlling solenoids that require more current than a PIC will provide?
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solenoid valve model #
what is the model # of your solenoid valve ?
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Answer: Model of solenoid valve in our design
bogdan,
Our PIC microcontroller must control a latching valve solenoid, Model L 1/180 1/4"x1/4" as described at http://www.giplindia.com/pdf/water-valve-catalogue.pdf . Here is a description from this document and why we think it is the right choice for use with a microcontroller and battery operation. BTW, why do you ask?
"Brief Design Guide:
Life of battery (1.5 V DC X 4 Nos. alkaline) is about 250 000 cycles (only valve
operations).
Latching valve operates upto 5 V DC, 60 mS pulse. Hence cicuit should have cut off
voltage or battery low / replace battery indication sutabley.
It is prefered to mount latching valve in coil up right position.
As supply voltage goes higher pulse width decreases.
40 mS pulse is optimum pulse width for valve operation from CLOSE to OPEN
position. For OPEN to CLOSE pisition, pulse width of 20 mS may be kept. This will
maximize battery life.
Circuit employed in operation of valve should be of high quality and should have
minimum current consumption in stand by mode to maximise battery life.
Test figures mentioned in this document is based on 6 V DC obtained using 1.5 V X 4
Nos. alkaline batteries."
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http://www.mcmanis.com/chuck/robotic...t-circuit.html
http://www.cadvision.com/blanchas/hexfet/np-s.htm
http://www.4qdtec.com/h.html
The simplest 4 transistor h bridge:
http://library.solarbotics.net/circu...arHbridge.html
If you do not believe in MAGIC, Consider how currency has value simply by printing it, and is then traded for real assets.
.
Gold is the money of kings, silver is the money of gentlemen, barter is the money of peasants - but debt is the money of slaves
.
There simply is no "Happy Spam" If you do it you will disappear from this forum.
|
My current approach using H-Bridge solenoid control??
Joe: I studied the H-Bridge circuit and I can see now why it is probably the preferred choice for microcontroller use with motor control, and I presume it can be applied in same manner for controller of latching solenoids. Therefore, I have redone our design as shown in the attached schematic, in which we propose to use a ROHM H-Bridge IC model BD6211 or BD6221, depending on what battery voltage we select for solenoid control (see http://www.rohm.com/products/databoo...x_series-e.pdf for data sheet). This IC can be purchased for $1.50 USD at Mouser and greatly reduces the cost and simplifies the circuit layout as compared to using relays. What is your opinion of this schematic?....will it work to control the latching solenoid without fear of "shoot through" during startup of the MCU while it is being initialized and the MCU pin logics are not yet stabilized? At this point that is my only concern about using the H-bridge for latching solenoid control.
Thanks so much for this tip!
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