Will this circuit work?

[dist1nct]

For a class project I'm trying to create a light controlled lamp, but I was hoping to check with everyone here to see if it would work (I found the diagram online) and also where I could position the photocell so it is not effected by the light it is powering. Thanks.

 

[DerStrom8]

For a class project I'm trying to create a light controlled lamp, but I was hoping to check with everyone here to see if it would work (I found the diagram online) and also where I could position the photocell so it is not effected by the light it is powering. Thanks.

If you're trying to control the brightness of the lamp by adjusting the light on the sensor, than you don't want a relay. The relay is either on or it's off. There is no in-between. In order to control the brightness of the lamp, you'll need to have varying voltage/current. You can't really do that with a relay.

 

[dist1nct]

If you're trying to control the brightness of the lamp by adjusting the light on the sensor, than you don't want a relay. The relay is either on or it's off. There is no in-between. In order to control the brightness of the lamp, you'll need to have varying voltage/current. You can't really do that with a relay.

How would I alter the circuit diagram then to make this more plausible? Thanks for the response!

 

[DerStrom8]

How would I alter the circuit diagram then to make this more plausible? Thanks for the response!

Well I don't really have enough information. What kind of lamp are you using?

You might be able to simply replace the relay with the lamp, but like I said, it depends.

 

[dist1nct]

Well I don't really have enough information. What kind of lamp are you using?

You might be able to simply replace the relay with the lamp, but like I said, it depends.

Well, I've only just started with this project so much has not been decided, including the lamp. So, whichever lamp you think would be easiest/most appropriate. What information can I give you to help?

 

[DerStrom8]

Just about any small 12 volt lamp should be okay. It also depends on what battery you're using. An automotive light bulb might work. Just a small one, like from a dome light. Don't try a headlight

 

[dist1nct]

Just about any small 12 volt lamp should be okay. It also depends on what battery you're using. An automotive light bulb might work. Just a small one, like from a dome light. Don't try a headlight

So I would be able to replace the relay with an automotive light, and that should (in hopes) work?

 

[DerStrom8]

So I would be able to replace the relay with an automotive light, and that should (in hopes) work?

I'm afraid I'm not very good with analog circuits. Perhaps someone else here is more qualified to help you in this matter. I think the circuit you posted is actually supposed to switch the lamp directly on and off, depending on the light input. I think the transistors set up a threshold--a point where the lamp would be full-on or completely off with the slightest change in light input. I think the idea you're thinking of would only need a single transistor, the base current controlled directly from the LDR.

Something else you haven't mentioned: do you want a direct light relationship, or indirect? Direct would mean that the less light sensed by the LDR, the dimmer the lamp will be. Indirect would mean that as the LDR senses less light, the bulb will get brighter.

What exactly are you using this circuit for? Any more information about what you're trying to do would be greatly appreciated at this point.

 

[dist1nct]

What exactly are you using this circuit for? Any more information about what you're trying to do would be greatly appreciated at this point.

Well, from what you tell me, what I'm trying to create is a indirect light relationship. I want to be able to control a lamp with this circuit, having it turn on (or get brighter, I don't mind which one) the darker it is in the room, and turn off (or dim) when it gets brighter in the room. As far as more information, unfortunately I have a very base knowledge of how circuitry works. I'm attempting to put this circuit together in Yenka to see if I can get it to work, but mostly everything I'm trying is trial and error, most likely a result of my extent of knowledge on the matter. I hope this makes sense, and sorry I can't provide much information.

 

[gtr_stitch]

Looking at the circuit, i would say that it's good. The relay would make it full-on or full-off, like strom said. If you remove the relay, then you should get a dimming effect. I made a very simple dark activated night light once, and the way it was set up, as ambient light faded, the night light slowly became brighter, but as the ambient light increased, the night light slowly went off. Schematic is below. It's a very very simple circuit.
Best of luck!

 

[MOR_AL]

Your circuit is a Schmitt trigger.
When LDR receives some amount of light, Q1 conducts more, cutting Q2 and Q3.
VR1 adjusts intensity of light level.
RL1 is NC
RL1 is there to increase load current or another load voltage.
Without RL1 Q3 may overheat if you change RL by your load (lamp).
Sorry my English!!
MOR_AL