Simple lighting effects generator

Simple lighting effects generator

Postby lynn » Mon Nov 05, 2012 5:55 am

Title: Lighting effects generator by Dmitriy Pankratiev

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A simple lighting effects generator. In sprite of its simplicity, this device is capable to generate tens of recurring effects.

The basis of the device is a multi-bit digital sequence generator that is implemented on a serial shift register [1]. The repetition period of the sequence is determined by the number of bit of a register and much higher than the repetition period clock. For a sequence containing all possible states of the register, excepting the zero state (so-called M-sequence) the value of the period is Tn = (2n-1) / f, where n - number of bit of a register, f - clock frequency in Hz. A type of a generated sequence (the actual number of combinations of states bits in one period) depends on the structure of the feedback, which is constructed with using of modulo-2 adder logical element in each loop. In the simplest case a single item is used.

Download the circuit diagram of lighting effects generator in English (high resolution bmp, 80Kb) ... ff_gen.bmp

Referring to the concept of the device. The master oscillator is made on the logical elements of DD1.1, DD1.2 and transistor VT1. A generation frequency is controlled with variable resistor R2 within 5...50 Hz. From the generator output pulses are passed to the clock input of 8-bit register DD2. The register is enveloped by the feedback loop through modulo-2 adder (element DD1.3). DD1.4 element is used in a feedback loop to set the register to the initial state that must be different of zero. Here is used an element property to be a repeater with the logic 0 level on one of the inputs and with the log.1 level on the input to be an inverter of state of another one. When the power is on the register is setting to zero state, and both input and output of DD1.3 have a level of the log.0. VT2 transistor is opening by a current pulse through capacitor C2, and the output level of element DD1.4 is setting to logic 1 for a charging time of the capacitor. In the first (or all that depe nding on clock speed) register bits a level of logic 1 is being stored. At the end of charging of the capacitor and locking VT2 the digital sequence generator is running in normal mode. By an experimental way it's found the best case to connect the inputs of the adder to 5th and 8th bits of the register (14 and 20 pins of DD2). That provides the maximum length of the generated sequence and, correspondingly, the greatest number of combinations of states of the register. The output of each register bit is used to control a powerful key that can be assembled according to any scheme matched to TTL. This version of device uses optically isolated triac control circuit (MOC30xx types).

In the practic it is running over all the known light effects alternately ("running light", "running shadow", and other combinations). If desired, the number of channels can be reduced to one (flashing with a pseudorandom frequency), however, a set of effects will be reduced too considerably.

It is not required to ajust the correct assembled device. It is only necessary to set the desired frequency range of the oscillator by selection of a capacity of C1.

[1]. "Digital noise generators" M.Marder, V.Fedosov. "Radio" (Moscow), № 8/90, p.68.
[2]. "Design of discrete devices on integrated circuits", G.I.Puhalsky, T.Ya.Novoseltseva. "Radio and Communications", Moscow, 1990
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