Schematic Reference

Friday, October 17, 2014

Single IC Dual tones Siren Circuits Diagram

Double-tone Police sound Circuits Diagram

This circuit is intended for children fun, and can be installed on bicycles, battery powered cars and motorcycles, but also on models and various games and toys. With SW1 positioned as shown in the circuit diagram, the typical dual-tone sound of Police or Fire-brigade cars is generated, by the oscillation of IC1A and IC1B gates. With SW1 set to the other position, the old siren sound increasing in frequency and then slowly decreasing is reproduced, by pushing on P1 that starts oscillation in IC1C and IC1D.

The loudspeaker, driven by Q1, should be of reasonable dimensions and well encased, in order to obtain a more realistic and louder output. Tone and period of the sound oscillations can be varied by changing the values of C1, C2, C5, C6 and/or associated resistors. No power switch is required: leave SW1 in the low position (old-type siren) and the circuit consumption will be negligible.

Single -IC Dual-tones Siren Circuits Diagram

Parts:

R1,R3___470K   1/4W Resistors

R2______680K   1/4W Resistor

R4_______82K   1/4W Resistor

R5______330K   1/4W Resistor

R6_______10K   1/4W Resistor

R7_______33K   1/4W Resistor

R8________3M3  1/4W Resistor

C1,C5_____10µF  25V Electrolytic Capacitors

C2,C6_____10nF  63V Polyester Capacitors

C3_______100nF  63V Polyester Capacitor

C4_______100µF  25V Electrolytic Capacitor

D1-D3___1N4148  75V 150mA Diodes

IC1_____4093   Quad 2 input Schmitt NAND Gate IC

Q1______BC337   45V 800mA NPN Transistor

P1______SPST Pushbutton

SW1_____DPDT Switch

SPKR____8 Ohm Loudspeaker

B1______6V Battery (4 AA 1.5V Cells in series)

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iPod Controlled Sports Car

One of the most interesting things you can do with the iPod touch is using it as a remote control for other devices that is why some created remote control applications.

Hacks and Mods: IPod Controlled Sports Car

The entire device was rewired to allow the owner to start the car, open the doors and trunk, roll down the windows, control the radio, the car alarm and even the engine. The range of this is limited because the communication is through Bluetooth. What makes this car different from other remote controlled; it can be controlled via voice commands.

Hacks and Mods: IPod Controlled Sports Car

It is conceivable that an iPod touch could replace the fanciest of universal remotes and it is worth a try for all the hobbyists out there.

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Fog Lamp Sensor Circuit Diagram

For several years now, a rear fog lamp has been mandatory for trailers and caravans in order to improve visibility under foggy conditions.

Circuit diagram :

Fog Lamp Sensor Circuit Diagram

When this fog lamp is switched on, the fog lamp of the pulling vehicle must be switched off to avoid irritating reflections. For this purpose, a mechanical switch is now built into the 13-way female connector in order to switch off the fog lamp of the pulling vehicle and switch on the fog lamp of the trailer or caravan. For anyone who uses a 7-way connector, this switching can also be implemented electronically with the aid of the circuit illustrated here.

Here a type P521 optocoupler detects whether the fog lamp of the caravan or trailer is connected. If the fog lamp is switched on in the car, a current flows through the caravan fog lamp via diodes D1 and D2. This causes the LED in the optocoupler to light up, with the result that the phototransistor conducts and energises the relay via transistor T1. The relay switches off the fog lamp of the car.

For anyone who’s not all thumbs, this small circuit can easily be built on a small piece of perforated circuit board and then fitted somewhere close to the rear lamp fitting of the pulling vehicle.

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Para saki the QRP Transceiver fact Diodes Circuit Diagram

This circuit is a dream of 40 years was conducted, a transceiver QRP (low power) done without transistors, IC or valves, its creator just used diodes. The receiver has little gain, but works well for strong signals via the audio amplifier which is very effective.I believe this transceiver is at least very curious, though precarious it sure works and shows that the electron has no limits.

Para-saki the QRP Transceiver fact Diodes Circuit Diagram

Parasaki the QRP Transceiver fact Diodes Circuit Diagram

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Simple Water Alarm Schematic

The LM1830 fluid detector IC from National Semiconduc tor is designed to be able to detect the presence of fluids using a probe. This chip requires a relatively high supply voltage and is not the most frugal power consumer. It is also quite specialised so unless you are buying in bulk the one-off price is not cheap.

An alternative circuit show n her e uses a standard CMOS IC type 74HC14. It has the advantage of operating with a 3 V supply and consumes less than 1 µA when the alarm is not sounding, this makes it ideal for use with batteries.

Water Alarm Schematic Circuit Diagram
Simple Water Alarm Schematic

The 74HC14 has six inverters with hysteresis on their input switching thresholds. A capacitor (C1) and a feedback resistor (R1) is all that’s necessary to make an inverter into a square wave signal generator.

In the water alarm circuit the feedback resistor consists of R1 and the water sensor in series. R1 prevents any possibility of short-circuit between the inverter’s input and out-put. Resistor R2 defines the inverter’s input signal level when the sensor is not in water. Any open-circuit (floating) input can cause the inverter to oscillate and draw more current.The remaining inverters in the package (IC1.B to IC1.F) drive the piezo buzzer to produce an alarm signal. Capacitor C2 ensures that no DC current flows when the circuit is in monitoring mode (with the alarm silent) this helps reduce the supply current.

A micro-switch can also be substituted for the water sensor to make the circuit a more general purpose alarm generator. link

Author: Roland Heimann - Copyright: Elektor

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USB 5V to 12V DC DC Step Up Converter by LT1618

This is a 5V to 12V DC-DC step-up (boost) converter circuitry that is especially ideal for the USB powered applications. First of all a USB port has two current supply modes. Before detecting the connected device, it supplies maximum 100mA to the load. After recognizing the device, it increases the output current up to 500mA. In this circuit, controller (LT1618) also provides two input current modes. 100mA and 500mA input modes can be selected by the user.

USB 5V to 12V DC-DC Step-Up Converter by LT1618

Output currents are limited due to the increased potential difference at the output. When the demand of the load increases, output voltage will start to decrease. For example, if the circuit operates in the 100 mA input mode, when the load is 35 mA, the output voltage will be kept at 12V. But if the load increases to 50 mA, output voltage will reduce to 8V to maintain the constant 100 mA input current.

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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 circuit for home power amplifiers with power rating of around 0.5W. The circuit 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 circuit.

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 circuit works off regulated 12V. You can also power it through a 12V rechargeable battery.

Assemble the circuit 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

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