CKS2006
electronic carnary song bird
If you love the lovley and sweet sound of a warbling sone bird, but donot like to clean the cage. How about trying this electronic canary. It's battery opterated and is a very good singer. When switched on the bird starts to whistles going down scale for a momont then breaks into a warble for several seconds then it shuts off only to start again by its self automaticlly in a few more seconds.
How it works: the schematic is shown in the following circuit. The transistors Q1,Q2 forms a astable multivibrator with the associated time constants. Whats not so obvious is the blocking oscillator also with main components are Q2, C2, and T2. This produces the warble. When power is applied the bias of Q1 is satuated and Q2 is off. The capacitor C1 is initally discharged: but as it begins to charge through resistor R3. Transistor Q2 becomes forward biased buy the current through transformer T1 and R4. Sooner or later Q2 functions as a blocking oscillator and Q1 does the same because of the coupling through capacitor C5. During the oscillation C1 is charged in a negative way as the result of the half-wave rectification pwerduced by Q2(which in turn is reverse biased while during the negative half-cycles). The charging current is very large at the beginning and slops off while C1 charges. Transformer T1 inductance changes from a low value to a larger one this is because of the decressing core saturation. The output tone then decreases in the pitch. The capacitor C1 moves rapidly in the negative direction in respect to ground, and its causing the biasing of Q2 is subutude by the action of this oscillator itself. While during the positive half-cycles and the charging current through capacitor C4. While during the negative half-cycles. Eventually capacitor C4 charges to a point where its contribution in the biasing of Q2 is small and the base-emitter junction of this transistor is reverse biased during a biger portion of each succeeding cycle eventually at some point the blocking oscillator starts to "squegg" that is to say capacitor C2 with its charge accumulated by it during the negative half-cycles is big enough that Q2 is cut off compleatly until its charge leaks off. When the charge does leaks off transistor Q2 can oscillate once again. This charge-discharge cycle happens so fast that the audio tone generated sounds like a warbling bird. Capacitor C4 finally is discharge to the point it has no contirbution to the biasing of Q2, And eventully turns off. with Q2 off transistor Q1 turns on and the cycle starts over again.
It should be noted, that components values should be followed closelly as one component value change will through the rest ofv the circuit off. If you change one value you will have to chang the rest to compensate the results of how it works and a differint outcome will result. Also note that resistor R8 is needed and donot omit this is so there is a lesser load on the functional circuit. A higher impedance speaker will do the same thing. The transformers specisications as follows first T1 has 10K prtmary and a 2K secondary, T2 has 500 ohm center tap primary and a 8 ohm secondary. If you canot find a parts suppler for the two transformers you can find them in a old pocket transistor radio.
electronic carnary song bird
If you love the lovley and sweet sound of a warbling sone bird, but donot like to clean the cage. How about trying this electronic canary. It's battery opterated and is a very good singer. When switched on the bird starts to whistles going down scale for a momont then breaks into a warble for several seconds then it shuts off only to start again by its self automaticlly in a few more seconds.
How it works: the schematic is shown in the following circuit. The transistors Q1,Q2 forms a astable multivibrator with the associated time constants. Whats not so obvious is the blocking oscillator also with main components are Q2, C2, and T2. This produces the warble. When power is applied the bias of Q1 is satuated and Q2 is off. The capacitor C1 is initally discharged: but as it begins to charge through resistor R3. Transistor Q2 becomes forward biased buy the current through transformer T1 and R4. Sooner or later Q2 functions as a blocking oscillator and Q1 does the same because of the coupling through capacitor C5. During the oscillation C1 is charged in a negative way as the result of the half-wave rectification pwerduced by Q2(which in turn is reverse biased while during the negative half-cycles). The charging current is very large at the beginning and slops off while C1 charges. Transformer T1 inductance changes from a low value to a larger one this is because of the decressing core saturation. The output tone then decreases in the pitch. The capacitor C1 moves rapidly in the negative direction in respect to ground, and its causing the biasing of Q2 is subutude by the action of this oscillator itself. While during the positive half-cycles and the charging current through capacitor C4. While during the negative half-cycles. Eventually capacitor C4 charges to a point where its contribution in the biasing of Q2 is small and the base-emitter junction of this transistor is reverse biased during a biger portion of each succeeding cycle eventually at some point the blocking oscillator starts to "squegg" that is to say capacitor C2 with its charge accumulated by it during the negative half-cycles is big enough that Q2 is cut off compleatly until its charge leaks off. When the charge does leaks off transistor Q2 can oscillate once again. This charge-discharge cycle happens so fast that the audio tone generated sounds like a warbling bird. Capacitor C4 finally is discharge to the point it has no contirbution to the biasing of Q2, And eventully turns off. with Q2 off transistor Q1 turns on and the cycle starts over again.
It should be noted, that components values should be followed closelly as one component value change will through the rest ofv the circuit off. If you change one value you will have to chang the rest to compensate the results of how it works and a differint outcome will result. Also note that resistor R8 is needed and donot omit this is so there is a lesser load on the functional circuit. A higher impedance speaker will do the same thing. The transformers specisications as follows first T1 has 10K prtmary and a 2K secondary, T2 has 500 ohm center tap primary and a 8 ohm secondary. If you canot find a parts suppler for the two transformers you can find them in a old pocket transistor radio.