Solving Remote Control Challenges: Introducing the Timer Circuit
In certain video cameras, a remote control socket labeled W exists, yet connecting and interval-controlling this socket often proves to be a challenge. A prime example is the Blaupunkt 8010 camcorder, which doesn’t follow conventional power on/off methods but requires precisely timed pulses lasting 40–60 ms. One pulse activates the camera, while the subsequent pulse deactivates it, rendering manual operation nearly impossible. Fortunately, the timer presented here serves as an effective solution to this dilemma.
Automated Pulse Generation: Flexible and Low-Power Timer Design
This timer circuit simplifies the process by automatically generating the required pulses. Users can adjust the interval between two pulses, setting it anywhere between 1 s and 10 s. Operating on a 9 V (PP3 or 6F22) battery, the circuit exhibits minimal power consumption, drawing a mere 330 μA. This design ensures efficient and reliable remote control functionality for video cameras equipped with the challenging W socket.
Circuit Operation: Activating the Camcorder
With the closure of switch S1, indicated as signal A in Figure 2, the circuit’s operation begins. A differentiating network comprising R2 and C1 ensures that IC2a receives a brief pulse, depicted as signal B, even if S1 remains closed for an extended period. Assuming the circuit was inactive before the closure of S1, pin 1 of IC2a is in a high state, causing the output of the IC to go low, producing signal C. This output signal from IC2a serves as the trigger for monostable IC1a through AND gate D2, D3, and resistor R3. Consequently, the output of IC1a, illustrated as signal E, activates transistor T1, which functions as the stop/start switch for the camcorder. The drain and source of T1 are linked to the camera.
Time Interval Measurement: Precisely Timing the Sequence
Simultaneously, IC1b is triggered by IC1a to initiate the measurement of the time interval between the start and stop pulses. This interval can be preconfigured using P1. Throughout this timeframe, signal H remains low, deactivating switch S1. Once the monostable time of IC1b has elapsed, signal H transitions to a high state through IC2d. This, in turn, triggers IC1a, leading to the transmission of a stop pulse to the camera. Following this, the circuit reverts to its dormant state, awaiting the closure of S1 to repeat the process.
As drawn, the circuit is particularly suitable for adding titles to the filmed material. One touch on the S1, and the title in front of the camera lens is recorded within a few seconds. Switch S1 may be replaced by an interval time for making speeded-up recordings.