Need Help In Understanding The Circuit Diagram

Replies

• 

  JAIHO

  I see a couple of transistors ( NPN AND PNP ) , and 12v power supply. Resistors resist the current.
  You need some kind of data sheet to understand the whole diagram , i think..
  sorry .
• 

  randypang

  oh sorry, i forgot to put the parts list.
  
  r1r4r7r10 = 3.3k
  r8r9 = 27k
  r2r3r5r6 = 68k
  r11 = 560
  c1 = 1000uf / 16v (microfarad)
  c2c3 = 22uf / 16v (microfarad)
  c4 = 0.47uf (microfarad)
  c5c6 = 22nf
  t1t2t3t4 = bc547
  t5 = TIP112 / KT829
• 

  sauravgoswami

  I think its a pre-amplifier,not sure i will have to check!!!
• 

  randypang

  its a martin siren project. just wanting to know how the circuit operates.
• 

  sauravgoswami

  well,they seem toi be emitter follower circuits,not sure i will have to check
• 

  Harshad Italiya

  I think this is more than the Pre- Amlifier Circuit (yes it is) but it Generates Perticular Frequency at the output of Last Transistor and according to that the LS gives output.
• 

  reachrkata

  Here goes - Refer:Multivibrator
  
  1) The circuit with T1 and T2 is an Astable multivibrator with frequency is given by 0.721/R3C3
  F = 0.5Hz (approx)
  
  2) The circuit with T3 and T4 is also an Astable multivibrator but here R8 and R9 are connected to the output of the first multivibrator instead of 12V. therefore the frequency of the second vibrator would depend on whether input at R8/R9 is 12V or 12V potential divided by R6/R5. The frequency will be higher when output of first vibrator is logic 0, because charging time of R8C5/R9C6 is much faster.
  Exact frequencies need calculation.
  
  3) This signal is driven into the speaker.
  
  In a nutshell, T3-T4 generates the Audio frequencies, while the change of Audio frequency is controlled by T1-T2.
  
  - Karthik
  
• 

  randypang

  hey there reachrkata,
  
  thanks for the explanation of the circuit 😀
  
  how do i get about knowing the frequencies at the transistors (t1,t2,t3,t4).
• 

  sauravgoswami

  I think now it will be easy for you to figure out the circuit and study accordingly!!!
• 

  reachrkata

  This link should give you an idea of the design procedure of an Astable and also what the frequency is.
  
  Designing An Astable Multivibrator | PDF | Electronic Engineering | Analog Circuits
  
  -Karthik