WARM AS THE FIREPLACENice in the dark frosty evening to sit by the radiant heat of the heater. But it becomes more comfortable when in it, like in a real fireplace, flickering “flame” and crackling “wood”. However, the industrial designs, simulation of burning firewood slowly, and all attempts to improve the installed impeller foil give only partial improvement results.
Noticeable effect can be achieved using electronic devices that simulate the burning and crackling wood in the fireplace. The scheme is simple, performed on the available element base and can be easily repeated.
The device consists of a generator of “white noise” amplifier, frequency divider, host light source control simulator “crack” of wood and power supply.
The generator of white noise, assembled on the transistor VT1, resistors R1 — R6, diode VD1, capacitors C1 — C3, produces a signal, the amplitude and frequency of which randomly change. This signal is supplied to the level control (variable resistor R7), and further the findings 12 and 13 of k176ie12 circuit. Feature of application of this IC is that its generating part performs the functions of audio amplifier. In the chip amplified signal is supplied to the frequency divider, which is every 256 pulses alternately switches the level logical 1 at the outputs T1 — T4. The positive voltage pulses from these outputs through resistors R9 — R12 are received in the same sequence to the control electrodes of the SCRs VS1 — VS4, open them, causing sequential ignition of the lamp HL1 — HL4 installed in the heater behind a decorative panel with an image of wood. With the conclusion of 6 DD1 signal is sent to the simulator of the crackling wood, performed on the transistor VT2, resistors R13 — R15 and phone BF1.
Schematic diagram of the electronic simulator.
Schematic diagram of the electronic simulator.
As the reference for the chip selected signal, the amplitude and frequency of which change randomly, and the frequency of the flickering lamps and the volume crackle will also be constantly changing, creating the effect of “burning of wood” in the fireplace.
The power supply transformer T1, diodes VD3 — VD6, the Zener diode VD2, capacitors C5, C6 and the resistor R16 is made according to the traditional scheme and in the description is not needed.
The simulator is assembled on a printed circuit Board size 112X92 mm, made of foil fiberglass thickness of 1.5—2 mm.
Circuit Board device with the layout of the elements.
Circuit Board devices with the layout of the elements.
When handling the chip series К176 should take precautions to avoid exposing it to static electricity. The soldering tip must be connected to the common wire of the device and grounded. First fluster the terminal 7 of IC, then 14, then the rest of the findings.
Diodes: VD1 any of a series of D2, D9, D18, VD3 — VD6 — any of a series of D226. SCRs КУ201Л, КУ202Л, M or other, the calculated switching voltage is not lower than 300 V.
Resistors R1, R7 and R13 — JS4-1, R16 — MLT-0,5, the rest of the MLT-0,125. The capacitor C4 type CSR-2, the oxide can be K50-6, K53-1, K53-4 and others.
The power transformer is made on the yoke Ш10Х20. The winding of I contains 4500 turns of wire PEV-1 to 0.05; II — 250 turns of PEV-1 is 0.23. Incandescent lamps it is advisable to use low power, for example 25 or 40 watts. Telephone — resistance of 50-200 Ohms (for example, TM-4, TDK-1).
Adjustment of the device begin with the generator of “white noise”, whose characteristics depend on the properties of germanium diode VD1. In parallel with the resistor R7 connected piezoelectric phones or an oscilloscope and apply voltage. If the generator does not work, try to reverse the polarity of the switching diode, to set the transistor with a large coefficient of transfer of current or increase the voltage to 12 V (the power supply replace the Zener at Д815Д). Further, the resistor R7 set the required signal level at terminals 12 and 13 of the chip, achieving the desired frequency and brightness of the flicker of the lamps. Last set simulator “squid wood”, adjusting the variable resistor R13 and by choosing the values of capacitor C4.
A. CHARKIN, Bolshevo, Moscow region.

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