This is a 0-10V DC to AC dimmer. The problem is a big jump when supply from 4V to 5V DC to the input so the output voltage comes from 60V to 130V AC. This is not good, if anyone has any idea how to change it I will be happy. I cannot use the No.5 pin on the 7555 IC, which is used to Soft Start.


Update to clarify:

It is not important what is on the load. It is important to improve the jump from 60 to 130. I provide you only with a brief summary as the whole circuit is complicated and very hard to explain. Theoretical thinking or run circuit simulation will give you wrong value and not give you the solution.

I have two ways first remove Q1, C 10 nF & 100 k second adding op-amp but it means require add small transformer because whole circuit operate on around 5 mA. If add another IC will mean add 12 V transformer or use high wattage resistors it will complicated idea. I expect something not conventional maybe just idea something very simple to improve only.

  • If remove Q1 it means 0 = max on output 10 V, in = ~ 20 - 70 V adj. via P2 with 240V AC.
  • With Q! 0=20-70 V AC on output & 10 V in 230 V AC on outputs.

    enter image description here

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    \$\begingroup\$ You need to preview the question before blindly typing. \$\endgroup\$ – pipe Oct 20 '17 at 13:08
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    \$\begingroup\$ Welcome to EE.SE. (1) Please edit your question to fix the link. (2) Embed an image of the schematic in the question so that we can read it in the question. (3) Please read your sentences again and fix the punctuation. (4) Ask a question ending with a question mark. \$\endgroup\$ – Transistor Oct 20 '17 at 13:18
  • \$\begingroup\$ In any case, dimmers don't work by varying the output voltage. \$\endgroup\$ – Finbarr Oct 20 '17 at 13:19
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    \$\begingroup\$ That's not true, @Finbarr, and isn't enough information to avoid confusing the OP. Dimmers can be made in linear format which reduce the voltage. Triac dimmers adjust the RMS voltage using phase-control. LED dimmers adjust the voltage or current - depending on the LED unit - by PWMing the power. This adjusts the RMS voltage or current to give the required lighting level. \$\endgroup\$ – Transistor Oct 20 '17 at 15:28
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    \$\begingroup\$ @Jeff. I have fixed a bunch of typographical errors and added some paragraphs and punctuation to your update. Please review by hitting the "edited ..." link to see if the corrections are OK. Please read the comments carefully and try to answer them all in your post. Note that Q1 can never turn on as there is nothing to pull the base low. \$\endgroup\$ – Transistor Oct 22 '17 at 16:51

You have a few problems.

  1. Your schematic has wires running across chips and between the plates of a capacitor! This is going to make it difficult for anyone to debug - including you. It needs a clean-up.
  2. You need to give designators to each component so we can discuss them. i.e., R1, R2, C1, C2, Q1, Q2, etc.

enter image description here

Figure 1. 0 - 10 V control input.

  • It appears that you are trying to use 0 - 10 V control to drive an opto-isolator LED. LEDs don't respond linearly to voltage but rather to current.
  • With 2k permanently in series the most you could possibly get is 10 V / 2k = 5 mA into the LED. Is this enough to turn it on?
  • It is not clear how the 4N25 and Q are supposed to affect the 555 timer.
  • It is not clear what kind of load you are driving. Tungsten lamp or LED?
  • It is not clear what AC voltage the circuit is running on.

Fix the schematic, repost and add some explanation of how you expect it to work and what problems you are seeing.

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