Auto reversing polarity after a few milliseconds (for solenoid control)

[Harald Kapp]

I remember the old "bed lamp switch" which is press for on and press again for off.(latching)
Maybe this has a similar mechanism internally.

That's what I was thinking about, too. This would not require reversing the polarity, but Adam's tests indicate otherwise.

 

[Adam Rendek]

oh, and one more thing: when I tested the valve, I installed in under my sink so it was under pressure. The wires were dangling and I switched it on and off by touching the battery bank's ( 4 x AA) wires briefly, swapping the wires and touching them briefly again. So unfortunately reverse polarity seems to be needed and having it under pressure does not make a difference.

 

[Bluejets]

Ok...the microswitch arrangement I mentioned earlier will do if you just need manual switching.

 

[Harald Kapp]

Ok...the microswitch arrangement I mentioned earlier will do if you just need manual switching.

I think the idea of the pulsed operation of the valve's coil is to reduce power consumption (and possibly overheating of the valve's coil). The manual switch should work with respect to reversing the polarity aas required, but will operate the coil continuously causing high energy loss and heating of the valve's coil.
Plus this circuit will not work with the touch sensor.

In addition to the full hardware idea I linked to, a very simple microcontroller circuit can be used.
Feed the output of the touch sensor to an input of teh microcontroller. Let the microcontroller do the necessary sequencing and timing of the output signals to an H-bridge as proposed by bluejets in post #2.

 

[CDRIVE]

It's unfortunate that Alec's two circuit contributions (Posts 16 & 17) is beyond Adam's comfort zone. They're reminiscent of Kris' circuits that usually were discrete as possible and always evoked a smile because they contained an element of "clever".

Adam, if you want really simple it can be done using Alec's concept (capacitor charge & discharge to produce a '+ -' pulse) in conjunction with a (DPDT) Toggle Switch. Yes, I realize that it's not as elegant as a touch switch but one Switch, one Cap is certainly simple.

Chris

 

[CDRIVE]

MPJA is a favorite supplier of mine which stocks this at direct from China prices but you will have to pay shipping.
http://www.mpja.com/H-Bridge-Power-Driver-Dual-Channel-L9110/productinfo/31596+MP
MPJA's part number is different than this Datasheet for that H-Bridge but it's the same item.
http://me.web2.ncut.edu.tw/ezfiles/39/1039/img/617/L9110_2_CHANNEL_MOTOR_DRIVER.pdf
The schematic indicates pullup resistors on the inputs. So, bringing any input low should power the solenoid and change the output polarity dependent on which one of two pins (each channel) is brought low. If I'm not mistaken I would think that two push-button switches would be all you would need to complete your task. In operation power to the solenoid would be provided only as long as each button is (closed) depressed.

Since I'm sure you're still desirous of using a single capactive touch switch this H-Bridge could work with what we call a Flip-Flop that can change states with each press of a single switch. These may be available in board module form also.

Chris

 

[Harald Kapp]

I found this module. This module could be controlled by the touch sensor:
touch 1: relay on
touch 2: relay off
The relay on the module should be replaced by a DPDT relay. This relay would be used to reverse the polarity. A second relay, not part of the module would be controlled by the touch sensor, too, to create the on pulse for the valve.

The whole thing will work like this:
When the touch sensor is activated, the relay on the module ensures correct polarity (normal / reversed) for the on/off operation of the valve.
The second relay controls power to the relay on themodule, thus ensuring that power is applied only while the touch sensor is active.

 

[Bluejets]

Harold, The microswitches are momentary contact so no overheating or excessive current drain would occur.

 

[Harald Kapp]

The microswitches are momentary contact

I'm sorry, this wasn't obvious to me.

 

[CDRIVE]

Harald, I see that the seller is in Germany but after reading the product description (Pigeon English) it looks more like a Chinese seller with a Germany address.

Chris

 

[Harald Kapp]

Based on my location I get results in German or for Germany. Sometimes it is difficult to find results in English. I think when "1 Channel Latching Relay Module 5V with Touch Bistable Switch 1 Channel Latch" is used as a set of keywords any search engine will turn up similar results for the respective location.

 

[CDRIVE]

That was just a knee jerk reaction after reading the description. Most of the world does a reasonable job of translation into English; with exception of the Chinese. No matter though. I regularly purchase direct from China items on Ebay because their prices are just one level above them paying me to buy it!

Chris

 

[CDRIVE]

Harald, I thought I'd post the description as I see it in English. This is only because you may see it in German. Chinese descriptions always makes me smile...

Description:


1. Power supply to meet the scope , DC 5V;

2. The power required by the by -line diagram , is not reversed , although the protection circuit , but not for a long time reversed ;

3. Product regulator slight fever is a normal phenomenon , long working hours have a normal relay heat phenomena are normal ;

4. Relay load power to give leave some margin should avoid high-power ( about 2000W) and long working environment , there will be some impact on the life of the product .



Features :

1. Double panel design PCB;

2. Chips made ??using stable and reliable control , stable and reliable performance , strong anti-interference , not false triggering , performance is superior than the CD4013 ;

3. Regulator has the power to provide adequate and stable voltage , and have enough vents to ensure stable and reliable product for a long time to work ;

4. With anti- reverse protection diode power , reverse power for a short time without any damage to the product ;

5. Use SONGLE genuine relay control load in 250V 10A ( AC ) and 30V 10A ( DC ) under load can withstand ;

6. Has a touch switch as product testing , stability testing of products directly ;

7. Can also trigger an external trigger switch , the products have a connection with a good seat and lead , more convenient to use ;

8. Triggering sensor module can also be used to do other triggers , are valid as long as the trigger is low , there are more functional expansion;

Chris