This project flashes eight LEDs in an apparently random manner. It uses a 4060 combined counter and display driver IC which is designed for driving 7-segment LED displays. Circuit diagram : Simple 8 Random Flashing LEDs The sequence is not really random because seven of the LEDs would normally be the display segments, the eighth LED is driven by an output that is normally used for driving further counters. The table below shows the sequence for the LEDs. You can use less than eight LEDs if you wish and the table may help you decide which ones to use for your purpose.
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Build a Park Assist Circuit Diagram . This is a Simple Park Assist Circuit Diagram. This Park Assist circuit was designed as an aid in parking the car near the garage wall when backing up. LED D7 illuminates when bumper-wall distance is about 20 cm., D7+D6 illuminate at about 10 cm. and D7+D6+D5 at about 6 cm. In this manner you are alerted when approaching too close to the wall. All distances mentioned before can vary, depending on infra-red transmitting and receiving LEDs used and are mostly affected by the color of the reflecting surface. Black surfaces lower greatly the device sensitivity. Obviously, you can use this circuit in other applications like liquids level detection, proximity devices etc. Simple Park Assist Circuit Diagram
A simple stereo audio amplifier is built around two 7905 negative-voltage regulators (IC1 and IC2) and a few discrete components. The circuit will also work with other 79XX regulators if appropriate power supply is used. Regulator IC 7905 works as an amplifier for the voltages applied to common pin2 (Ground or GND). Also check the LM317 audio amplifier, another interesting circuit. The minimal voltage drop over the standard 7905 is around 2V and it depends on the output current. Feedback resistors in the IC set the gain of the channel internally. The amplifier is a class-A audio amplifier. The minimal applicable value of R3 for the regulator 7905 is 8.2 to 10 ohms per 5W. Circuit diagram : 1W Stereo Amplifier with Voltage Regulators Circuit Diagram If the required output current for LS1 is below 100 mA, the value of resistor R3 can be 33 to 51 ohms per watt. The circuit works with any load resistance (R3 in parallel with LS1 as the load) under the condition that the regulator is ...
This is a project of Simple Mains Voltage Monitor Circuit Diagram. Many electronics hobbyists will have experienced the following: you try to finish a project late at night, and the mains supply fails. Whether that is caused by the electricity board or your carelessness isn’t really important. In any case, at such times you may find yourself without a torch or with flat batteries. There is no need to panic, as this circuit provides an emergency light. When the mains fails, the mains voltage monitor turns on five super bright LEDs, which are fed from a 9 V battery (NiCd or NiMH) or 7 AA cells. A buzzer has also been included, which should wake you from your sleep when the mains fails. You obviously wouldn’t want to oversleep because your clock radio had reset, would you? When the mains voltage is present, the battery is charged via relay Re1, diode D8 and resistor R10. D8 prevents the battery voltage from powering the relay, and makes sure that the relay switches off when the mains vol...
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 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. Resis...
Modern PCs rarely have a serial or parallel port any more, to the great regret of any-one who experiments with microcontrollers every now and then. In the old days it was very simple to use the parallel port of a standard PC and program just about any type of AVR microcontroller with it. When you want to do that now, you’re first obliged to buy a programmer that communicates with the PC via USB, which immediately raises the threshold of getting started with these microcontrollers. The circuit presented here offers a solution to this. Simple USB AVR-ISP Compatible Programmer Circuit Diagram : As you can see from the schematic, this is a very simple circuit, built around a cheap, standard AVR microcontroller plus a handful of passive components. You may have already observed that this microcontroller does not have a USB interface and the circuit does not use a USB to serial converter either. The strength of this circuit is found in the firmware. The USB interface has bee...
Measure AC mains voltage without using a multimeter. All you need to do is to slightly modify the light dimmer fitted at the base of a table lamp for use as a voltmeter . When the dimmer is turned anticlockwise to a point where the filament glow is just visible, that point can be used as the reference point for measuring the voltage. Light dimmer Circuit Diagram First, remove the old knob and fix a circular white paper around the shaft. Now put back a skirted knob with a cursor as close to the paper as possible and mark two extremities of the pot on the paper as CW and ACW (see Fig. 2). AC volts scale marking Switch on the lamp via a variac and feed 50 volts. Rotate the potmeter knob anticlockwise until the filament glow is just visible and mark that point against the cursor as 50V. Keep on increasing the voltage to 100, 150, 180, 200 and 220 using the variac and calibrating the scale for all the voltages. Now a voltage scale is created. The only snag is that the voltage is increasing ...
Proximity Detector Circuit Diagram. This proximity detector is constructed using an infrared diode detector. Infrared detector can be used in various equipment such as burglar alarms, touch free proximity switches for turning on a light, and solenoid-controlled valves for operating a water tap. Briefly, the circuit consists of an infrared transmitter and an infra-red receiver (such as Siemens SFH506-38 used in TV sets). The transmitter part consists of two 555 timers (IC1 and IC2) wired in astable mode, as shown in the figure, for driving an infrared LED. A burst output of 38 kHz, modulated at 100 Hz, is required for the infrared detector to sense the trans mission; hence the setup as shown is required. To save power, the duty cycle of the 38kHz astable multivibrator is maintained at 10 per cent. The receiver part has an infrared detector comprising IC 555 (IC3), wired for operation in monostable mode, followed by pnp transistor T1. Upon reception of infrared signals,...
Pyroelectric Fire Sensor -Circuit-Diagram. Here is an ultra-sensitive fire sensor that exploits the direct piezoelectric property of an ordinary piezo element to detect fire. The lead zirconate titanate crystals in the piezo element has a property to de-form and generate an electric potential plifier with gate protected p-channel. MOSFETs in the inputs. It has high speed of performance and low input current requirements. There are two inputs—the non inverting input (pin 3) connected to the piezo element through diode D7 (OA71) that carries the volt-age signal from the piezo element and the inverting input (pin 2) that gets a momentarily changes the voltage level at pin 3 of IC1 and its output swings high. Transistor T1 conducts taking the reset pin 12 of IC2 to ground. IC2 is now enabled and start oscillating. With the shown values of the oscillating components C3 (0.22) and R8 (1M), when heated, thus converti...
This Electronic Circuit Project of high voltage generator circuit. This high voltage generator was designed with the aim of testing the electrical break-down protection used on the railways. These protection measures are used to ensure that any external metal parts will never be at a high voltage. If that were about to happen, a very large current would flow (in the order of kilo-amps), which causes the protection to operate, creating a short circuit to ground effectively earthing the metal parts. This hap-pens when, for example, a lightning strike hits the overhead line (or their supports) on the railways. This generator generates a high voltage of 1,000 V, but with an output current that is limited to few milliamps. This permits the electrical breakdown protection to be tested with-out it going into a short circuit state. The circuit uses common parts throughout: a TL494 pulse-width modulator, several FETs or bipo...
Common electromagnetic relays with coil voltage of 5V, 6V or 12V can operate power circuits in the range of 250 to 300 volts and up to 20A. The actuating current of these relays is in the range of 50 to 100 mA. In many applications, such as temperature-controlled equipment, energisation/de-energisation of 5V, 6V or 12V relays for ‘on’/‘off’ control of the load is to be achieved by a few millivolts. Circuit diagram : Simple Relay Actuating Circuit Diagram Here is a simple relay actuating circuit that can be used to energise relays with a few millivolts as the input. As shown in the figure, the circuit is built around op-amp µA741(IC1) followed by an emitter follower using transistor 2N3440 (T1) and a few discrete components. You can change the sensitivity required (when the input is in millivolts range) to energise the relay by changing the value of resistors R1, R2 and R3. In all the cases, values of R4, R5 and R6 remain unchanged. Resistor R8 is basically a current-limiting res...
This is a Simple Gate Alarm Circuit Diagram . This a cheap and simple gate alarm made from a single CMOS Integrated Circuit. That is intended to run off a small universal AC-DC power supply . Simple Gate Alarm Circuit Diagram IC1a is a fast oscillator, and IC1b a slow oscillator, which are combined through IC1c to emit a high pip-pip-pip warning sound when a gate (or window, etc.) is opened. The circuit is intended not so much to sound like a siren or warning device, but rather to give the impression: "You have been noticed." R1 and D1 may be omitted, and the value of R2 perhaps reduced, to make the Gate Alarm sound more like a warning device. VR1 adjusts the frequency of the sound emitted. IC1d is a timer which causes the Gate Alarm to emit some 20 to 30 further pips after the gate has been closed again, before it falls silent, as if to say: "I'm more clever than a simple on-off device." Piezo disk S1 may be replaced with a LED if desired, the LED being wired i...
This is a Simple Low-voltage Power Supply Circuit Diagram . If you want to check the behavior of an electronic circuit at low voltages, an adjustable power supply as shown here may be helpful. Powered from a 3 to 16 volts source (DC for sure), it will provide a stable output voltage in the 0 to 1.5 V range. Simple Low-voltage Power Supply Circuit Diagram Multiturn trimpot P1 allows the output volt-age to be adjusted with good precision. The BC337-400 output transistor raises the out-put current to about 200 mA bearing in mind that the minimum supply voltage is 3.5 V. The transistor’s dissipation should be taken into account, and a more power ful t ype used if necessary. T1 may be omitted and R2 replaced with a wire link if you are happy with 3 mA at 3 volts out, 10 mA at 6 V or 20-30 mA at 10-16 V. These values represent the maximum output current of the TLC271 op amp. Without T1, the minimum supply voltage is 3.0 V.
A very simple light alarm schematic circuit project can be designed using some common electronic parts, as you can see in the circuit diagram bellow . This light alarm schematic circuit project will sound as soon as the drawer is opened and light falls on the Darlington phototransistor. The output alarm may be redesigned to activate a relay or triac. This simple light alarm schematic circuit project use a MAL12 LDR photoresistor as a sensor . Light Alarm Schematic Circuit diagram The 14011 quad , 2 input, NAND gate is wired up to oscillate when the input to it goes high, that is the BC557 transistor turns on after light is detected by the MAL12. The oscillating output from the 14011 turns the BC547 on and off , making the buzzer to sound. After the alarm has started and it is put back into dark conditions , alarm will continue to sound for about 3 - 5 seconds. This is due to the 1uF capacitor and 4M7 resistor which keep the input to the 14011 high . The circuit is very simple and must ...
A very simple real time clock electronic project can be designed using the PIC16CXXX microcontroller family , designed by Microchip Technology . This real time clock electronic project uses the Timer1 module, from a mid-range PIC16CXXX microcontroller, to control a low-power real-time clock. Timer1 was chosen because it has its own crystal which allows the module to operate during sleep. Upon power-up, the device is initialized with the display starting at 12:00 PM, and Timer1 is configured to generate an interrupt (every second). The Timer1 overflow interrupt wakes the device from sleep. This causes the time registers (HRS, MIN, SECS) to be updated. If the SECS register contains an even value (SECS = 0), the colon (":") is not displayed. This gives a visual indication for each second. Then the device returns to sleep. Real Time Clock Circuit Diagram For setting the clock are used three keys : SELECT_UNITS Key (S1) selects which units are to be modified (hours, minutes, off)...
A very simple 4 channel video amplifier electronic circuit project can be designed using NJM2582 ic suitable for video applications with SCART connector . Design of the circuit is very simple and require few external electronic parts . Simple 4 Channel Video Amplifier Circuit diagram Some features of the NJM2582 are : Operating Voltage ±5V, +5V, +11V ; 6input 4output , 2input 1output Video SW , Internal LPF , 6dB Amplifier , Internal 75Ω Driver Circuit , DC output for SCART (FUNCTION SW, BLANKING) .
Here is electronic project of Simple Electronic Door Buzzer has a very simple function and is very easy to build. This door buzzer circuit use a LF351 operational amplifier and other few common electronic components. When the S1 push-button is depressed an initial positive voltage is placed on the C2 and the non-inverting terminal of the LF351 operational amplifier and the circuit will oscillate at a low frequency. Simple Electronic Door Buzzer Circuit Diagram: The used speaker for this project must have a impedance between 40 -80 ohms. The door buzzer electronic circuit needs to be powered using a 9 volts DC power supply.
The LED bicycle light that we described in the July/August 2009 edition of Elektor has proved very popular. The author was particularly struck by the basic design, but as always, there is room for a little improvement! Below we describe two enhanced variations on the original theme. Both circuits are, like the 2009 original, powered from a 6 V (rechargeable) battery, shown here as Vl. The simpler of the two circuits, which consists of four transistors, is in function essentially the same as the original version. lt takes the form of a boost converter with feedback provided by the voltage drop across a current sensing resistor, in this case R2. A value of 6.2 O for R2 is suitable for use with four white LEDs at D4 to D7, and gives an LED current of approximately 20 mA. The 250 mW Zener diode D10 is provided to limit the output voltage in the case that the LED chain should go open-circuit, pulling the gate of the MOSFET to ground via T3, T1 and T2 if the output voltage exceeds the br...
This is a Simple Complementary metal–oxide–semiconductor connect switch circuit diagram , CMOS technology is used in microprocessors, microcontrollers, static RAM, and other digital logic circuits. This connect switch does not rely on mains hum for switching-It-can be used with battery powered circuits. Simple Cmos Connect Switch Circuit Diagram Schmitt trigger IC1 forms a 100 kHz oscillator and IC2a which is biased into the linear region, amplifies the output and charges CI via the diode. IC2b acts as a level detector. When the sensor is touched, the oscillator signal is severely attenuated which causes CI to discharge and IC2b to change state.Sourced by : Circuitsstream