Photo Flash

Kodak Flash circuit

This flash circuit is a typical camera flash. ..

disposable camera strobe light

If you have no idea what is a "strobo", "strobe", "stroboscopy" or whatever way it is called, it is simply a flashing light. It is usually used on police cars, 'disco' places and many interesting applications, including scientific ones. This project is dangerous because it implicates high voltages, it can be lethal. Please read the Disclaimer about my articles: Use this material as educational only, do not build this project unless you know what you are doing and under your own risk. What I'm trying to say is: Don't be stupid, you can kill yourself. After using a disposable camera, is possible to remove the film for develoment and use the camera to build an easy, cheap and cool strobe light...

This discussion covers 3 different Xenon flashing circuits from disposable cameras. From them, you will learn circuit tricks that have NEVER been shown in any theory book. The first circuit covers 6 BUILDING BLOCKS. You will need an old "disposable Flash Camera" plus two extra parts to carry out the modifications...

This 9v battery powered circuit is designed for remote control flash needs. A charge control circuit turns off the high voltage generator when the photoflash capacitor is fully charged. A neon lamp is included to indicate when the system is ready to flash...

This is the matching transmitter for the air transparency monitor receiver. The transmitter launches powerful 1000-watt light pulses that last about 20 microseconds...

This line powered xenon flash circuit drives a small camera type flash tube. It has an optical isolator to allow the flash to be safely triggered from some remote device. A flash rate of 2Hz is possible with the circuit...

The stoboscope tube needs about 250-400V DC to operate. This high voltage is generated using simple voltage step up circuit built from transistors Q1,Q2 and transformer T1. This circuit gives out about 230V AC voltage which is then rectified with rectifying bridge U1 (must have at least 400V voltage rating) and stored to the main capacitor C1. I built my stroboscope from parts taken from old camera flash unit. This approach gave me nice flash tube with reflector, trigger transformer and some of the capacitors (for example C1). Other parts were the one luying around. I used some strange triac I found in my for the triggering circuit, but any triac which can handle at least 1A and 400V should do the job well...

This Adjustable Strobe Light is the bigger brother of the plain old strobe light. This one uses a much more powerful "horse shoe" Xenon tube which produces more light. You can also control the flash rate up to about 20Hz. Do not look directly at the flash tube when this thing is on! # T1 and L1 are available from The Electronics Goldmine (see Where To Get Parts). This ciruits is NOT isolated from ground. Use caution when operating without a case. A case is required for normal operation. Do not touch any part of the circuit with the case open or not installed. Most any diodes rated at greater then 250 volts at 1 amp can be used instead of the 1N4004`s. Do not operate this circuit at high flash rates for more than about 30 seconds or else C1 and C2 will overheat and explode. There is no on/off switch in the schematic, but you can of course add one...

In order to determine when exactly to flash the strobe, we compare the running average signal to a strobe signal threshold. Whenever the signal is above the strobe threshold, the system flashes the LEDs, which we used as our light source. An outline of the beat detection algorithm is as follows: Pass music through low pass filter and amplify filtered signal (Figure 1). Add 2V DC offset to signal to elevate signal to effective range of ADC. Take samples of low-passed music with ADC and full wave rectify. Average current value with previous and take derivative and full wave rectify resulting signal. Pass differential signal through running average filter (later values weighted more). Keep track of the maximum level of the running average and calculate threshold based on this max value (dynamic threshold). Compare current sample value with threshold-if signal above threshold flash strobe. Strobe flash if sample is greater than threshold, then return to Step 1..

This DC-DC converter ("inverter") needs nothing but unmodified Radio Shack parts. You don`t need to build or wind any coils or transformers. This is a cheap-and-dirty experimenter`s circuit. I tested this and it worked for me, but I disclaim all warranties! The LM386 audio amplifier, R1 and R2, and C1 and C2 are used to make a crude Wien bridge oscillator. The R1-R2-C1-C2 network has minimum loss and no phase shift at approx. 3.5 kilohertz and serves as the positive feedback route for the oscillator. If an automatic gain/level control circuit was added to keep the oscillation from building up to the point that the LM386 clips, this circuit would be a sinewave oscillator. Instead, the oscillation rapidly builds up to where severe clipping occurs...

Figure 1 shows a complete circuit for an emergency lamp that operates from a 12V automotive battery. The xenon flash tube requires a 250V-dc anode voltage and a 4-kV trigger pulse. To generate the 250V dc, IC1, a switching regulator controller, and T1, a standard Versa-PAC transformer, operate in the discontinuous-flyback mode. With this configuration, circuit efficiency is typically 75 to 80%. R1 and IC1`s internal-sense-threshold voltage limit the peak primary current to 1.6A. The R2/R3 divider and IC1`s internal 1.25V reference at the VFB Pin determine the maximum-voltage setpoint. To generate the 4-kV trigger pulse, a standard cold-cathode- fluorescent-lamp (CCFL) backlight transformer, T2, operates in the forward mode. IC2, a dual MOSFET driver, functions as a 1-Hz oscillator and a one-shot for the trigger pulse for Q2...

Flash slaves are used when you need to supplement one flash unit with one or several more. This slave trigger simply triggers those other units. It does this by "seeing" the first flash (using a phototransistor) and triggering the other flashes a few microseconds later. The sensitivity of the circuit is adjustable to compensate for ambient light or dimmer than usual master flashes. Q1 should be aimed at the master flash. R1 should be adjusted for maximum sensitivity but no false triggering. Keep your fingers away from SCR1 when the circuit is operating. It is at 50V-300V and will give you a nasty shock...

Put two Teccor K1300E70 sidacs (Digi-Key catalog number K1300E70-ND) in series. NOTE - when ordering these, it is a good idea to get some K1200E70`s and some K1100E70`s just in case you need slightly lower voltage sidacs. Solder the series pair of sidacs across the trigger contacts of the board. The board is now a repeating strobe. The sidacs are devices that are essentially open circuit until a critical voltage is reached, then they switch into a nearly short circuit condition. They are basically improved diacs. When the flash board develops approx. 260 volts across the trigger contacts, the sidacs switch on and this causes contact between the trigger contacts to be made. Once the bard flashes, the sidacs return to their open-circuit state. I recommend putting the series pair of sidacs over the little hole in the pea-sized round marking where the lens was...

The following reference design outlines the key considerations in the construction of a solid
state, high performance flash solution utilizing Luxeon® LED technology. This design integrates Lumileds high power Luxeon Flash product with a cost effective lens solution to provide the necessary light output and illumination pattern suited to digital still camera (DSC) and cell phone camera flash applications. An example of a Luxeon Flash implementation is described and the expected practical output performance is summarized. Additional recommendations considering the mechanical design, thermal management and electronic drive circuitry are provided to assist rapid design and development of a functional camera flash solution for space
constrained applications such as cell phones and PDAs. Finally, the light output color spectrum of the Luxeon Flash is compared to requirements for expected use in combination with CMOS and CCD image sensors...

Many high end PDAs and smart phones have adopted color LCD screens. These LCDs are usually illuminated using white LEDs as a backlight. Since white LEDs require a higher voltage than the typical battery voltage, a boost circuit is required to boost the battery voltage. Many smart phones and PDAs also include a digital camera. Many of these cameras utilize an LED flash that helps illuminate the subject in a dark environment. The schematic below shows the application circuit. In this circuit an SC-70 Dual NMOS (Fairchild FDG6303N) device is used to switch on the flash LEDs. The flash LEDs are set for a current of 83mA (as determined by the value of R6). The backlight LEDs are dimmable by either a logic PWM signal applied to the PWM input or a DC adjust voltage applied to the DC_ADJ input...