When the firebox of the fireplace or stove at the cottage of wood raw material for the process of combustion from time to time it is necessary to control: to throw the wood, to increase traction and D. Replace "owner's eyes" and to recall this may offer electronic the device, signaling the decrease of the flame in the furnace (the furnace).
I'm a little poeksperimentiroval and found that the infrared detectors, it turns out that even respond to a burning match with very little infrared (IR) radiation. But this knowledge was the impetus for development of devices for the control of combustion. In bright flame at a distance of 1.5 m from the fire alarm silent. Once the fire in the stove or fireplace will start to fade - sound the alarm. And here, for example, with the use of flash flash lamp IFK-120 (and tiny flash built into modern cameras) reaction device no.
To assemble such a device is easy even an Amateur without much experience and get pleasure from work, well-deserved pride from the creation of useful the instrument with their hands and gratitude from the household.
The most expensive item in the device - infrared detector (IR) - worth about 80 rubles. But it can be used from the old receiver remote control, installed in the TV. Such detectors have started complete color television receivers back in the late 80-ies of the last century, fit and taken from there to the detector (receiver Board itself do not need). In modern TVs also have similar IR-detectors - and they will fit for this design.
Electric diagram of the electronic warning device
The supply voltage of the device is in the range of 5-7, due to technical characteristics of the infrared sensor. The voltage can be increased, for example up to 12 In, adding to the scheme is the simplest limiter-stabilizer consisting of Zener XA (or similar, for example ВZХ55С) and included consistently with him limiting resistor the resistance of 0.82-1 com. The anode the Zener diode is connected to GND and a connection point of the Zener diode (cathode) and the resistor connects to pin 2 of the sensor IF1. When this voltage serves a restrictive resistor. The current consumption of the device does not exceed 25 mA, 20 mA, of which "picks up" the sound capsule.
The principle of operation
Oxide capacitor C1 smoothes the noise in a power supply. Normal conditions sensitive the IR detector is a small high level at the output (pin 3 IF1). If in the area of "ownership" of the detector there is IR signal on pin 3 detector contains negative pulses. Polar capacitor C2 is to reduce the influence of random and extraneous interference. It is particularly necessary when in the same room there is a radio with remote management (usually they use the infrared spectrum to transmit a signal to the the distance, for example, the alarm device installed in the living room and supervises the work fireplace). If the device is used in the bath (and where such interference unlikely), C2 is expedient to exclude from the scheme of Negative pulses small amplitude insufficient to control the sound (and even light) alarm or relay. Therefore, passing the peak detector elements R1, VD1, they arrive at the gate field-effect transistor VT1, performing the role of the amplifier current. The transistor controls the audio earpiece with built-in sound generator frequency (AF) - HA1.
At the end of the furnace chimney, the detector can be disabled with the switch SВ1.
The device is in adjustment is not needed. Oxide capacitor C3 in this circuit an element providing a delay mute. It is necessary for ensure that the detector did not react to the flickering flame or short-term the reduction of combustion. So managed to achieve that "alarm" will sound only when the flames will really subside. More than the capacitance of the capacitor C3, the greater the inertia the alarm will to achieve. In very small limits the sensitivity of the device can be adjusted by changing the resistance of the resistor R1.
Details
The IR detector РRМ6936 can be replaced by ТSОР1736СВ1 or similar. Conclusions order consider, drawing detector convex side facing you. At the device ТSОР1736СВ1 1 and 2 conclusions are nearby, then through 2 mm from the second is third. The polarity of detector switching is not allowed.
Oxide capacitors - type K50-29 or similar. Field-effect transistor ВSТ70 you can replace ВS170 or the like. Both resistor - type MF-25. Diode VD1 you can replace KD522, D, CD with any letter index or foreign analogue 1N4148. Sound earpiece HA1 with a built-in generator AF on any voltage 3 - 6 V, for example TR-1203Y. The primer need to be included in the specified in the diagram polarity. Instead of, or in parallel with it you can include even low-power electromagnetic relay with a supply voltage of 5 V, for example TRU-5VDC-SB-SL. This solution may be useful for the future (see text below).
Elements in the scheme is so small that the circuit Board I designed, used standard perforated "blank" with metallized holes conclusions and inter-element connections are made using wire MGTF to 0.6. On the photo provided in the casing ready indicator (right - cap-HA1 alarm).
The ready indicator in the housing
Peculiarities and prospects of application
The device responds well to an open flame; at a distance of 0.5 m the alarm is triggered even in a lit match. This can be done a simple conclusion that on the basis of the proposed device can be manufactured fire detector. The principle of operation is the same - from open flame, and in the afternoon the efficiency of the detector is the same as that night because the device does not respond to light, not heat, not the flickering of the flames, and on the infrared component in the spectrum of fire, and it is time independent Especially need such an indicator may be outdoors, in open spaces, in forests, in villages, on the street. In these places a regular fire a sensor responsive to smoke, virtually useless. In cases where you want to control a powerful load (with current up to 6 a at 220 V), the load should be connected through the relay. For example, a submersible water pump.
The device can also be useful for controlling the operation of any remote management ("catches" both direct and reflected off the walls invisible man IR beam); for Troubleshooting and monitoring the operation of computer peripheral devices and cell phones that have an IR port; for "monitoring" premises, the store in which can be installed invisible man alarms that trigger when crossing the infrared beam (as in movies about agent 007) and in many other cases. The device is easy to Assembly.
Author: A. Kashkarov