Showing posts with label build. Show all posts
Showing posts with label build. Show all posts
Tuesday, September 9, 2014
Build a Wire Break Alarm With Delay Wiring diagram Schematic
Here is a simple schema of wire-break alarm that activates after a delay of 15 to 30 seconds. When the thin-wire loop running across the entrance door is broken, the alarm sounds after a delay of 15 to 30 seconds, the time period set through VR1. Thus the occupants get sufficient time to lock the room from the outside and catch the thief.
The schema uses CD4060, which is a 14-stage ripple-carry binary counter/divider and oscillator. It is wired as a timer here and does not need input pulse for trigger. CD4060 gets activated as soon as the power supply is switched on. Output O13 of CD4060 goes high after the lapse of preset delay set through VR1. Transistor SL100 (T2) is wired as a switch to power the timer section built around CD4060. When the wire loop is closed, transistor T2 does not conduct. So power to the timer schema is not available and the piezobuzzer does not sound.
Wire-Break Alarm With Delay Circuit Schematic
On the other hand, when the wire loop is broken by some intruder, transistor T2 conducts to power the schema and the piezobuzzer sounds after 15 to 30 seconds. IC1 can be reset by connecting the wire loop or interrupting the supply. The schema works off regulated 9V-12V. Assemble it on a general-purpose PCB and enclose in a metallic or plastic box of appropriate size. Connect piezobuzzer PZ1 through external wires and complete the installation.
Friday, September 5, 2014
build a Low Cost Stereo Level Indicator
Usually, Low-Cost Stereo Level Indicator home stereo power amplifiers don’t have output level indicators. An output power level indicator can be added to each channel of these stereo power amplifiers. As low levels of the output power are not disturbing and damaging to the people, there is no need to add a preamplifier and low-level detector before IC LM3915. But you should know when the output power becomes considerably high.
Here we present a very simple, low-cost stereo-level indicator schema for home power amplifiers with power rating of around 0.5W. The schema is built around two LM3915 dot/bar display driver ICs (IC1 and IC2). LM3915 senses analogue voltage levels to drive ten LEDs, providing a logarithmic 3dB/step analogue display.
Stereo Level Indicator Circuit Diagram
Here we present a very simple, low-cost stereo-level indicator schema for home power amplifiers with power rating of around 0.5W. The schema is built around two LM3915 dot/bar display driver ICs (IC1 and IC2). LM3915 senses analogue voltage levels to drive ten LEDs, providing a logarithmic 3dB/step analogue display.
Stereo Level Indicator Circuit Diagram
The voltage levels below 1V are not important because these correspond to a low level of the audio signal. Similarly, input voltage levels above 30V correspond to too high levels of the output power, which are not applicable for home power amplifiers. So the voltage levels of our interest are 1V to 30V, which can be handled directly with LM3915. LM3915 needs no protection against ±35V inputs, which simplifies the schema.
Most audio power amplifiers can drive 2-ohm to around 32-ohm loads. A load of several kilo-ohms will not change the conditions for the amplifier. CON1 is the input connector and CON2 output connector for the loudspeaker or headphone. Each channel has its own LM3915 and ten LEDs to indicate the power level. To indicate the different audio levels, select LEDs of three colours as per your liking. For example, you can have five green LEDs, three yellow LEDs and two red LEDs.
If appropriate signal generators and measuring equipment are not available, the level indicator can be calibrated based on personal observations. For example, the audio signal should be in the green LEDs zone when the signal is strong enough but not irritating, in the yellow zone when it is disturbing or starting to get distorted, and in the red zone when it is heavily distorted or too strong to listen to in the room.
Calibration can be done with the help of potentiometers VR1 and VR2, which are optional. Switches S1 and S2 let you select between two modes of LM3915 operation—the bar mode and the dot mode. These too can be removed or replaced with jumpers, if not required. When the switches are removed, leave pins 9 of IC1 and IC2 open.
The schema works off regulated 12V. You can also power it through a 12V rechargeable battery.
Assemble the schema on a general-purpose PCB and enclose in a suitable cabinet. Fix all the LEDs in two rows on the front side of the cabinet. Also affix the two terminals for input and output on rear side of the cabinet. link
Most audio power amplifiers can drive 2-ohm to around 32-ohm loads. A load of several kilo-ohms will not change the conditions for the amplifier. CON1 is the input connector and CON2 output connector for the loudspeaker or headphone. Each channel has its own LM3915 and ten LEDs to indicate the power level. To indicate the different audio levels, select LEDs of three colours as per your liking. For example, you can have five green LEDs, three yellow LEDs and two red LEDs.
If appropriate signal generators and measuring equipment are not available, the level indicator can be calibrated based on personal observations. For example, the audio signal should be in the green LEDs zone when the signal is strong enough but not irritating, in the yellow zone when it is disturbing or starting to get distorted, and in the red zone when it is heavily distorted or too strong to listen to in the room.
Calibration can be done with the help of potentiometers VR1 and VR2, which are optional. Switches S1 and S2 let you select between two modes of LM3915 operation—the bar mode and the dot mode. These too can be removed or replaced with jumpers, if not required. When the switches are removed, leave pins 9 of IC1 and IC2 open.
The schema works off regulated 12V. You can also power it through a 12V rechargeable battery.
Assemble the schema on a general-purpose PCB and enclose in a suitable cabinet. Fix all the LEDs in two rows on the front side of the cabinet. Also affix the two terminals for input and output on rear side of the cabinet. link
Wednesday, August 27, 2014
Build a 5V Supply Wiring diagram Schematic
This 5V Supply Circuit Diagram protects microprocessor systems from `brownouts` without the expense of an uninterpretable power supply. Designed around a small 9-V nickel cadmium battery the schema continues to provide a constant 5-V output during brownouts of up to a few seconds. Load currents of up to 500 mA may be drawn using the components shown.
With this mains-derived supply present, D5 is forward biased so that the stabilized supply powers the 5-V regulator and hence the schemary to be protected. FET Tj is held on by Dl, its drain current being provided from the dc supply via Rb and D2. Diode D3 is reverse-biased so that T2 is off, and the battery is isolated from D6. RCH and D4 serve to trickle charge the battery with approximately 1.2 mA.
5V Supply Circuit Diagram
When the 12-V supply is removed, Rl and Cl initially keep Tl switched on. D3 is now forward biased, so that Tl drain current is drawn via Rb, D3 and T2 from the battery. This switches T2 on, allowing the load schemary to draw current from the battery via D6 and the 5-V regulator. After a few seconds Cl has discharged (via Rl) such that Vgs falls below the threshold value for the FET, and Tl switches off. There is then no path for T2 base current, so that it also switches off, isolating the battery.
Build a Power supply Protection Wiring diagram Schematic
Why Build a Power supply Protection Circuit Diagram. When using a regulated supply to reduce a supply voltage there is always the danger of component failure in the supply and consequent damage to the equipment. A fuse will protect when excess current is drawn, but might be too slow to cope with over voltage conditions. The values shown are for a 12 V supply being dropped to 5 V.
Power supply Protection Circuit Diagram
The trip voltage is set to 5.7 V to protect the equipment in the event of a regulator fault. The 330 ohm resistor and the 500 ohm potentiometer form a potential divider which samples the output voltage as set by adjustment of the potentiometer. The SCR is selected to carry at least twice the fuse rating. The full supply voltage is connected to the input of the regulator.
The 2N2906 is held bias off by the 10 k resistor and the SCR so that the LED is held off. If the output voltage rises above a set trip value then the SCR will conduct, the fuse will blow, and the 2N3906 will be supplied with base current via the 10 k resistor, and the LED will light up.
Tuesday, August 26, 2014
Build a FM Booster Wiring diagram Schematic
A low-cost schema of an FM booster that can be used to listen programs from distant FM stations clearly. The schema comprises a common-emitter tuned RF preamplifier wired around VHF/UHF transistor 2SC2570 ( C2570). this FM booster schema is constructed using few common components( not require some special components ) and provide a very good gain .to calibrate this schema you need to adjust input/output trimmers (VC1/VC2) for maximum gain.
FM Booster Circuit Diagram Circuit Diagram
Input coil L1 consists of four turns of 20SWG enamelled copper wire (slightly space wound) over 5mm diameter former. It is tapped at the first turn from ground lead side. Coil L2 is similar to L1, but has only three turns. Both of the trimmers are 22pF value. This FM radio signal booster needs to be powered by a 12 volts DC power supply .
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