Electric Circuit Question

In the circuit diagram posted below, which one of these will work for the 50k ohm variable resistor circled in the picture ??

1.

2.

3.

4.

Also, how many watt resistors should I have to be safe ? Not just talking about the variable ones, but the others as well. currently i have selected 1/8 watts. is that a little low? or is it okay, since the output is going to a relay, not directly to the motors.

And what are the circle things? like the one right next to the bottom left C945 ? Is it a symbol for something I'm forgetting or just nothing, I should ignore it....?

Also, I am thinking the purpose of variable resistance is to correct for LDR errors ? As in both LDRs may not give same resistance at same irradiation, so to fine tune it...

thanks.


1474552d1410450308-electric-circuit-ques

[quote=“zedeneye1, post:, topic:”]

In the circuit diagram posted below, which one of these will work for the 50k ohm variable resistor circled in the picture ??

1.

2.

3.

4.

Also, how many watt resistors should I have to be safe ? Not just talking about the variable ones, but the others as well. currently i have selected 1/8 watts. is that a little low? or is it okay, since the output is going to a relay, not directly to the motors.

And what are the circle things? like the one right next to the bottom left C945 ? Is it a symbol for something I'm forgetting or just nothing, I should ignore it....?

Also, I am thinking the purpose of variable resistance is to correct for LDR errors ? As in both LDRs may not give same resistance at same irradiation, so to fine tune it...

thanks.

[/quote]

1) All 4 types are electrically equivalent. They differ only in physical appearance (or perhaps power rating). For your application, I would suggest WH06-2 type, which is screwdriver adjustable. You may also use SR083 type.

2) You don't need big Wattage because these are used to bias the transistors, only a few mA current will be flowing through them. The parts in the links can easily handle this current.

3) Circle things are connection points (not any physical electronic component). All circles marked with +12VDC should be connected together and then connected with +12V supply point.

4) The purpose of these variable resistors is to adjust the light level at which LDR will turn ON/OFF the transistor.

[quote=", post:2, topic:21508"]

1) All 4 types are electrically equivalent. They differ only in physical appearance (or perhaps power rating). For your application, I would suggest WH06-2 type, which is screwdriver adjustable. You may also use SR083 type.

2) You don't need big Wattage because these are used to bias the transistors, only a few mA current will be flowing through them. The parts in the links can easily handle this current.

3) Circle things are connection points (not any physical electronic component). All circles marked with +12VDC should be connected together and then connected with +12V supply point.

4) The purpose of these variable resistors is to adjust the light level at which LDR will turn ON/OFF the transistor.

[/quote]

1. How about the slide one? it seems fancier to me cuz of the slide, since I've never used a slide one before, only used trimmers...But I can't see the third pin on it...and that confuses me. It has 2 on one side and 2 on the other.

4. After the building the circuit and running it, if I realize that the thing is not pointing straight at the sun or light source, I can adjust these trimmers to get it right, is that correct? Especially since the LDRs may have a varying irradiation-resistance curve. Is that correct?

Thanks.

[quote=“zedeneye1, post:3, topic:21508”]

1. How about the slide one? it seems fancier to me cuz of the slide, since I've never used a slide one before, only used trimmers...But I can't see the third pin on it...and that confuses me. It has 2 on one side and 2 on the other.

4. After the building the circuit and running it, if I realize that the thing is not pointing straight at the sun or light source, I can adjust these trimmers to get it right, is that correct? Especially since the LDRs may have a varying irradiation-resistance curve. Is that correct?

Thanks.

[/quote]

1 - Slide one is not recommended. Typically, there will be variation in them over time and use and they would be more difficult to set precisely. Go with Ijaz's advice.

2 - Yes. The pots are being used to adjust the triggering point of the adjacent transistors. This is needed because LDRs are usually not well matched with regards to their response.

[quote=“Asad, post:4, topic:21508”]

1 - Slide one is not recommended. Typically, there will be variation in them over time and use and they would be more difficult to set precisely. Go with Ijaz's advice.

2 - Yes. The pots are being used to adjust the triggering point of the adjacent transistors. This is needed because LDRs are usually not well matched with regards to their response.

[/quote]

yeah I see how the slide would be more difficult to set with precision...

thanks.

[quote=“zedeneye1, post:5, topic:21508”]

yeah I see how the slide would be more difficult to set with precision...

thanks.

[/quote]

Progress with the Project please?

Aurangzeb

[quote=“aurangzebhaque, post:6, topic:21508”]

Progress with the Project please?

Aurangzeb

[/quote]

I've bought all the stuff. And it's been lieing there on the table for about a week now.

how do I find a motor that is slow enough? Like a geared motor that is very very slow.

Also I wanted to buy arduino board and some other stuff from http://www.ewallpk.com and http://arduinopak.com/.

The problem is they don't take cash on delivery like evselectro does. And I've never used this easy paisa stuff....

Do you know these two websites? Have you used any of them, any experience?

i bought USB programmer from http://www.ewallpk.com , the delivery charges were 150 i think and the product arrived 2 days afterwards.

[quote=“zedeneye1, post:7, topic:21508”]

I've bought all the stuff. And it's been lieing there on the table for about a week now.

how do I find a motor that is slow enough? Like a geared motor that is very very slow.

Also I wanted to buy arduino board and some other stuff from http://www.ewallpk.com and http://arduinopak.com/.

Do you know these two websites? Have you used any of them, any experience?

[/quote]

Finding a motor is tricky. Wiper motors used in large trucks maybe able to handle the wind loading. Here are two websites for your possible use.

http://www.scary-terry.com/wipmtr/wipmtr.htm

http://www.academia.edu/1017392/Fabrication_of_Dual-Axis_Solar_Tracking_Controller_Project

I suggest that you defer the purchase of the arduino until the circuit behavior is satisfactory. I can discuss details if you like during testing.

No information about the websites.

Aurangzeb