# Dark circuit using LDR

I have made this circuit but the problem is that I must attach the diagram of how all of these are connecting with each other

I have searched on the internet and I found that the second diagram looks like my diagram with some exceptions like R2 must not be used (this is my prediction)

Now could some please help me to say if these points are correct or not? A) The schematic diagram must show that one transistor is connected to next one by connecting emitter of one of them with collector or the emitter of both transistors are connected together?

B) the base of one transistor (left one) is connected with emitter or collector of another one(right one)?

• this appears to be a schoolwork question ... please show your work and explain what part you do not understand Dec 23, 2019 at 0:57
• @jsotola Because of "Dark sensor circuit by using two transistors", I think the OP doesn't have a clue about how to take the wiring diagram and place it into a proper schematic. Beyond that point, I cannot guess. But I think the OP wants help, knows that help won't come easily without an actual schematic, and is here asking for someone to do that. Doesn't feel like a homework question to me. Just feels like someone struggling a lot and at the very early learning stages. But maybe so. My crystal ball is still broken.
– jonk
Dec 23, 2019 at 1:00
• @jonk yes, actually I do not have a lot of experience about electronics, and I have tried several times to draw the diagram, but when I compare my diagram with the actual connection, I think there is a big difference between them, so I need some one help me to got this Dec 23, 2019 at 1:04
• Try it out, post it, then we will help you trace down your mistakes so that you could learn from them :) Dec 23, 2019 at 1:07
• @MohamedRami One important thing you need to learn is how to take wiring diagrams and turn them into readable, understandable schematics. When I first started out (and I'm still just a hobbyist without any training), the schematics that I saw at age 10 or 12 in magazines were wiring diagrams, not schematics. And very hard to read. I learned the hard way, on my own, about how to get rid of wires that didn't help me understand things, how to re-arrange parts, and the ideas related to a sheet of paper with signal flowing left to right and currents top to bottom.
– jonk
Dec 23, 2019 at 1:14

Q1 is reversed in physical layout.

As you said the LED R's should be shown. You could also put 4 Red LEDs in series like 4x 2V Zeners =8V and the current limit Series R can be 100 Ohms for 10mA.

Search for proper connections.

If using a different transistor , the pins may be different.

• Stewart Thank you so much Dec 23, 2019 at 4:29
• Does it work now? Dec 23, 2019 at 5:11
• I was going to note Q2 was flipped but you have done so. LEDs in 2S2P arguably better as 9V battery Vmax fades quickish. A comment that Rleft may need adjusting to set off/on point may be useful. A pot (or variable R) would be good Dec 23, 2019 at 5:42