Simple circuit - No ICs required, 12V Battery operation
This circuit was requested by several correspondents. Its purpose was to obtain more power than the siren circuit already available on this website (One-IC two-tones Siren) and to avoid the use of ICs. A complementary transistor pair (Q2 & Q3) is wired as a high efficiency oscillator, directly driving the loudspeaker. Q1 ensures a full charge of C2 when power is applied to the circuit. Pressing on P1, C2 gradually discharges through R8: the circuit starts oscillating at a low frequency that increases slowly until a high steady tone is reached and kept indefinitely. When P1 is released, the output tone frequency decreases slowly as C2 is charged to the battery positive voltage through R6 and the Base-Emitter junction of Q2. When C2 is fully charged the circuit stops oscillating, reaching a stand-by status.
Circuit Diagram:
Large ViewParts:
P1 = SPST Pushbutton Operating Switch
R1 = 1K
R2 = 10K
R3 = 1K
R4 = 220R
R5 = 10K
R6 = 220K
R7 = 22K
R8 = 100K
C1 = 22uF-25V
C2 = 22uF-25V
C3 = 10nF-63V
C4 = 47uF-25V
Q1 = BC557
Q2 = BC557
Q3 = BC337
B1 = 12V Battery
SW1 = SPST Toggle or Slide Main Switch
SPKR = 8 Ohms Loudspeaker
Notes:
P1 = SPST Pushbutton Operating Switch
R1 = 1K
R2 = 10K
R3 = 1K
R4 = 220R
R5 = 10K
R6 = 220K
R7 = 22K
R8 = 100K
C1 = 22uF-25V
C2 = 22uF-25V
C3 = 10nF-63V
C4 = 47uF-25V
Q1 = BC557
Q2 = BC557
Q3 = BC337
B1 = 12V Battery
SW1 = SPST Toggle or Slide Main Switch
SPKR = 8 Ohms Loudspeaker
Notes:
- A good sized loudspeaker will ensure a better and powerful output tone.
- As stand-by current drawing is zero, SW1 can be omitted and B1 wired directly to the circuit.
- Maximum current drawing at full output is about 200mA.
Source : www.redcircuits.com
1 comments:
Thank you for the great circuits this is a fantastic website I certainly will convey this to many other technicians I work with. Now I need to really ask a question. If sometimes you see a person lock their car and they then press a small remote the car's horn "BEEPS" once and when they return to deactivate the car alarm they press the remote and the horn "BEEPS" TWICE.
Please provide me with a little circuit I have my own build car alarm and I can only use the remote to swith my car alarm "ON" or "OFF" I want to hear the horn BEEPING as well thus the circuit mentioned above would be appreciated
many thanks for a great web site
Till next time
Chris Halgryn
Auckland
New Zealand
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