Author Topic: SIMPLE CONTOLER  (Read 5371 times)

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windrules

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SIMPLE CONTOLER
« on: September 19, 2004, 10:28:11 PM »
Would it be feasable to use a 12 volt zenner diode in series with a 12/240 volt solid state relay that turns on a simple 240 volt load on inverter.I think I would need a resistor also in series to say give me a control 13.8 volts.If this would work how do I work out resistor value? I have finaly got my genny working OK and need to control the thing.

Kind regards and thanks,

Mos
« Last Edit: September 19, 2004, 10:28:11 PM by (unknown) »

JW

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Re: SIMPLE CONTOLER
« Reply #1 on: September 19, 2004, 11:46:00 PM »
Yes, it is feasable. the solidstate relay you mention 12/240, if the 12 means 12vdc control voltage and the 240 means 240vac load voltage. Most figure that the most common AC solidstate relay need AC to control them, while this is true, some of these use DC to turn on and switch AC.


 Providing you have that (dc control) ,there is one other complication, the control circuit(dc)[in the relay] has a resistor built in to limit current already at 4 to 12v. These are made this way so direct battery 12v can be used to energise it without a limit resistor, such as a LED would need.


It certainly wont hurt to try putting a ziener(11.8v) in series with the control. You may just find you wont need the resistor added since the relay has one built in. You will have to just try and see, if anything the relay should protect the ziener(observe polarity on the diode). Its common when using stepped or progressive loads(in general) to use the same rated ziener for all the sucsessive circuits, then use resistors to make the different set points. You may be able to use a ziener that turns on at your desired load cut in 11.8 directly because a current limit resistor is already there.


 One other thing, as the load engauges, the batt volt will drop or swing, Depending how well you have "matched" your dump load. In some cases it is necessary to add a 12v to 6v regulator(like the type at radioshack that plug in your cig lighter socket in a car) for a stable refernce point. In this case you cant use a 11.8v ziener you have to use one in the 6v range. Then you get caught on that, because it never turns off, unless you have a wheatstone bridge referencing the 6v and the batt volts. the wheatstone bridge can control the ziener quite acuratly this way. And you may find a resistor works better than a regulator with wheatstone. This is the type of thing thats generally worked out with trial and error. If the dump load is sucsessive in steps many small loads, versa a large one things will be easyier(in reference to the voltage swing and varying wind). There are some dynamic condtions to deal with. A user a while back, kww was working with the idea of two or three sucessive loads, to deal with the voltage swing problem. Just remember there are 10,001 different way things can be done with these control circuits. And this is a variable requirement.


 Sounds like fun


JW  

« Last Edit: September 19, 2004, 11:46:00 PM by (unknown) »

ghurd

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Re: SIMPLE CONTOLER
« Reply #2 on: September 20, 2004, 12:26:29 AM »
Hi,


P.S. at the start. This may sound negative towards you and others. I don't mean it that way at all. I'm frustrated with it.


I'm trying to do the same thing, and in a simple way


The 12v zener uses, by definition, 12v. So if something on the other side of it needs 12v to turn on, the supply must be 24. 12vz + 12v(min turn on v) = 24v. A 12v zener and resistor fed 13v, the resistor only has 1v (13-12=1).


We got some almost good results with a 9v zener and a 5v relay (puting power to a 12v relay). Inconsistent operation.


You can get 13.7 or 13.8v zeners if thats somehow the magic number.


My problem has been the second it turns on, the load drops the battery V, which turns it off. The batteryV recovers, and it turns back on. The IC people would call it unstable occillation. They would also recommend a shoe box full of IC's to eaisly fix the problem. I'm sure it will work, but I'm lazy. I'd rather think about it for a year, then build something with 2 or 3 parts. Works for me.


Could you be thinking about it from the wrong perspective? What 'simple load' are you trying to turn on (what plugged into the inverter)? These guys have a lot of experience on running specific things. If its a water heater element, just get a 24v (not 12v because a 24v can handle and use the extra power if its extra windy) element and run it direct. If the genny is only making 1w at 6v, it still gets used, instead of waiting for the wind to get high enough for 12v. Just a simple example, probably not realistic.


Need more info. Post how if you get it to work without us.


G-

« Last Edit: September 20, 2004, 12:26:29 AM by (unknown) »
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ghurd

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Re: SIMPLE CONTOLER
« Reply #3 on: September 20, 2004, 12:39:14 AM »
JWs post came up while I was typing mine. Some of it is the same. Some of it I will try!
« Last Edit: September 20, 2004, 12:39:14 AM by (unknown) »
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drdongle

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Re: SIMPLE CONTOLER
« Reply #4 on: September 20, 2004, 05:10:49 AM »
You have a hysteresis problem. try adding a 741 op amp with a 555 timer the op amp provides a voltage comparator so you can tweek the sensitivity and the timer drives the relay providing a shut off delay to allow the battery to recover. Use the 9v Zener as a voltage reference for the 741.

No box of I.C's needed just 2, total cost for parts about $5.00


Carpe Vigor


Dr.D

« Last Edit: September 20, 2004, 05:10:49 AM by (unknown) »

JW

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Re: SIMPLE CONTOLER
« Reply #5 on: September 20, 2004, 10:33:33 AM »
I drew up a couple of very basic schmatics to describe my text in the above post. I want to stress these are "short hand". I figuired they would be more usefull than a verbal description.








-JW

« Last Edit: September 20, 2004, 10:33:33 AM by (unknown) »

windrules

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Re: SIMPLE CONTOLER
« Reply #6 on: September 20, 2004, 06:10:20 PM »
Thanks guys for your input.I think I will try the simple version first and go better if it does't work.I figure thre will be a bit of a delay switching inverter on and off anyway from standby so might give eneogh time not to be rediculous.First I will try just a few good old incadescents for the load and see what goes.

Regards,

Mos
« Last Edit: September 20, 2004, 06:10:20 PM by (unknown) »

JW

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Re: SIMPLE CONTOLER
« Reply #7 on: September 20, 2004, 08:15:31 PM »
A little note on the use of Wheatstone bridges, for segmentation(stepping) of load controls. When using rudementry voltage(input and reference) to the control, too several stepping loads is easy enough. However this relies on the liner arangement of bridge balence and succesive zieners(in parallel) to output control voltage[in reference] of the bridge balence.(of the wheatstone bridge)


There is a loophole here... A simple wheatstone bridge is made from 4 segments that are nothing more than 5% accurate [fixed]resistors wired in series(in a circle) with 2 parallel interfaces. If one of the fixed resistors(of the four) is replaced with a potentiometer, a variable configuration[center lead to one of the outside leads(reference to terminals)you only need 2 of the 3 leads] it IS possible to manually overide the bridge balence, this would be relative to the selected range of the potentiometer and it's rotational position[in degree's] which would force the bridge to balence, or un-balence at will, activating loads in sucesseion, depending on the angular setting, of the potentiometer. "This angular setting" option- of such a potentiometer, could be interfaced(syncronized) to bridge balence -directly with furling-, if mechanically coupled, at a 1 to 1, or 2 to 1 ratio, to  the furling's angular setting(bearing pivot) with a potentiometer wired into the wheatstone bridge.


So if you got a strong gust of wind the loads would activate before batery voltage would change. Or at least to as close to that as possible.

« Last Edit: September 20, 2004, 08:15:31 PM by (unknown) »

windrules

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Re: SIMPLE CONTOLER
« Reply #8 on: September 20, 2004, 09:32:34 PM »
Dr D. I am not too flash with electronics and ask if it would be possible to draw or explain how to wire up the 2 ics as I think this is probably to most simple way to do this as it gives some hysteresis (or whatever that word is),yet still sounds simple.I am OK with soldering iron but not too flash with circuits.

Regards,

Mos
« Last Edit: September 20, 2004, 09:32:34 PM by (unknown) »

drdongle

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Re: SIMPLE CONTOLER
« Reply #9 on: September 21, 2004, 05:33:01 AM »
I'll try to get you a schematic tonight.


Carpe Vigor


Dr,D

« Last Edit: September 21, 2004, 05:33:01 AM by (unknown) »

Nando

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Re: SIMPLE CONTOLER
« Reply #10 on: September 25, 2004, 01:41:02 PM »
Mos:


Yes but I would like to have more information from you before I open my mouth and tell you how to do it.


Please send the specification of the Solid State Relay (SSR),

The solid state relays may have a resistor internally in series with the LED circuit.


You also need to know the normal current the SSR needs to the resistor calculation ( also I can give you a different circuit that uses the AC but does not use much current using a capacitor, a small resistor, and 4 diodes).


Regards


Nando

« Last Edit: September 25, 2004, 01:41:02 PM by (unknown) »