Insulated-gate, field-effect transistor (IGFET), Q2 and silicon photo cell Zl form the heart of this circuit. Transformer T1 is an audio-output type, but it"s reversed in the circuit. A sudden flash from a photoflash unit detected by Zl sends a voltage pulse through the low-impedance winding of Tl via Rl. That voltage pulse is stepped-up in Tl"s 500-!l, primary winding before being rectified by Ql. Transistor Ql is used as a diode; its emitter lead was snipped off.....
This circuit gives multiple "stop-action" photographic effects like showing a bouncing ball in up to nine locations in a single photograph. The circuit will automatically fire the bulbs sequentially with the time between each firing variable. The circuit is functionally complete except for the actual firing system. In many cases, a simple SCR will work, as shown. The firing can be initiated in one of two ways..
Sound input to the microphone triggers the IC monostable circuit which subsequently triggers an SCR, and hence the flash, after a time delay..
This circuit is used for remote photographic flash units that flash at the~ame time as the flash attached to the camera. This circuit is designed to the trigger cord or hot shoe connection of a commercial portable flash unit and triggers the unit from the light produced by the light of the flash unit attached to the camera. This provides remoteoperation without the need for wires or cables between the various units. The flash trigger unit should be connected to the.....
Sound or light sensors corniected to J2 produce a voltage that is amplified by ICl-a and ICl-b. A positive trigger voltage that is developed by D1 and 1)3 and amplified by ICl-d, drives 1C2 and 1C1 to trigger SCR1. SCR1 is connected to a strobe. ..
The electronic darkroom timer is built around a 555 oscillator/timer, a pair of general-purpose transistors, a buzzer, and an LED. The 555 (Ul) is configured as an astable multivibrator (free-running oscillator). The frequency of the oscillator is determined by the values through i3 and Cl through C4. Switch SI is used to divide the capacitor network to vary the time interval between beeps; when SI is closed, the circuit beeps at intervals of 30 seconds. With SI closed,.....
Meter Ml, a +/-50-uA zero-center D`Arsonval meter movement is driven by Ul, a TL081 FET op amp, through R3. The gain of Ul is set at 11 by Rl and R2, while capacitor 01 is used to restrict the bandwidth of Ul to 1.6 Hz. Power for the circuit is derived from a simple dual-polarity 12- V power supply (consisting of Tl, D3, D4, 02, and 03). A light-dependent resistor (LDR), R16 (which is a semiconductor element whose resistance decreases as it is exposed to increasing.....
Ql is a phototransistor that is normally illuminated by a beam of light. When the beam is intercoupled, pin ..
Two gates of a 4011 arc used as a comparator. When the resistance of R4 decreases the voltage at pin 1 and 2 increases, producing a logic zero at pin 3, causing pin 4 to go high and activating the LED. R3 is calibrated in light units, or seconds exposure time. To calibrate, set pot R3 so as to just be on the LED ON/OFF threshold. With a light level that is suitable to correctly expose a photographic print,..
Transistor Ql remains off until the magnetic switch connected to Jl closes. When that happens, the 9 Vis connected through Rl to Ql"S base. Ql turns on, thereby charging C2 through relay Kl, which causes Kl "s contacts to close. Since the contacts connect viaJ2 to the remote control jack in the camera, which in tum connects to the camera"s shutter release, the closure of Kl"s contacts will cause the camera"s shutter to trigger. After C2 charges, Kl opens because.....
Take strobe-flash pictures the instant a pin pricks a balloon, a hammer breaks a lamp bulb or a bullet leaves a gun. Use a transistor amplifier of 1-watt rating or less. (It must have an output transformer) The amplifier is terminated with a resistor on its highest output impedance, preferably 16 ohms..
A 4001 CMOS Quad NORgate is set up as an astable multivibrator, which drives a simple differentiator and relay..
Phototransistor Ql receives a light pulse from a photoflash unit. The pulse is ac-coupled to amplifier Q2. It then triggers SCR1,..
By using a low-cost RS-170 camera and this circuit, a voltage that trades the position of an object in ..
Shutter speed tester combines frequency counter, crystal oscillator, and photo-transistor-operated gate generator. Oscillator pulses are counted as long as the shutter is open..
A flip of 51 puts the system in action. Power for the circuit is captured from the ignition switch, and circuit receives no power until the ignition switch is closed. When the camera is turned on, the capacitor C1 is charged and the emitter follower Darlington pair (formed by Q1 and Q2) are cut, so no voltage is applied to the relay (Kl), which serves as a load QL transmitter. normally open relay contacts are connected through the points of the vehicle. (At this point, the.....
One leg of the photocell (Rl) is tied to the +15 volt supply and the other end is connected to ground through resistor R2, forming a voltage-divider network. The non-inverting input of the 741 op amp, IC1, is tied to the junction formed by Rl and R2, while its inverting input is grounded through resistor R3. When switch SI is pressed, another divider network is formed, reducing the voltage applied to the inverting input of the op amp. When light hits the photocell its.....
This high-performance video-camera link transmits signals from your video camera to your VCR, or from your VCR to TVs throughout your home. The first stage of the rf chain is a crystal-controlled oscillator, Q1, with a frequency of 60 to 65 MHz, which is one-eighth of the final output frequency. The oscillator produces a signal of about +6 dBm (4 mW) that drives three stages of frequency doublers. The combined action of those doublers multiplies the input frequency by.....
The photo strobe slave trigger circuit uses a solar cell and an SCR to flash any strobe when you trigger your master strobe. ..
The NE555 circuit is a basic one-shot timer with a relay connected between the output and ground. It is triggered with the normally open momentary contact switch, which when operated, grounds the trigger input at pin 2. This causes a high output to energize Kl which closes the normally open contacts in the lamp circuit. They remain closed during the timing interval, then open at time out. Timing is controlled by a 5-M!lpotentiometer, R,. All timer -driven relay.....
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