Water Level Sensor Circuit Using LM1830 Single Chip

This is a water sensor circuit design using based on a Conductive Liquid Level Sensor, this single chip circuit is very compact and simple. This circuit is an ac excited fluid level sensor, which uses alternating current to provide biasing for the sensor probe to avoid electrolysis of the probes.  This ac excitation makes the sensing probe has longer lifetime. This circuit can be useful for wide range of water  or liquid level sensing  and control such as radiators, beverage dispensers, washing machines, water softeners,  irrigation, reservoirs, boilers,  aquarium,  or sump pumps

Many type of fluids are electrically conductive and can be detected using this liquid level sensor circuit: city water/ground water, sea water, chopper sulfate solution, weak acid, weak base, household ammonia, water and glycol mixture, wet soil, coffee,  or fruit juices. Remember that most of fuel doesn’t conduct electricity, so this circuit can be employed as fuel level sensor/detector. This is the figure of the circuit.

If we look at its data sheet, this water level sensor circuit chip is best at 10-24 volt supply voltage. The absolute maximum voltage supply for this liquid level sensor chip is 28V, but remembers to always try to avoid this extreme condition to prevent damaging the chip.

In the first circuit, a basic low level warning application uses a LED to indicate the water level falls below the sensor. You can see the filter pin (9) is not connected, this means that the LED is actually blinking at sound frequency, but it’s fine since our eye response is slow enough to notice such high speed blinking. Since without filter capacitor at pin 9 the output give a square wave signal, you can easily replace the led with loud speaker as shown in the second circuit to give audio indication. If you need a TTL or CMOS level then you should use a filtering capacitor connected to pin 9 and use the open collector output to drive a pull up resistor connected to a voltage supply at desired voltage level. For water level control, or any conductive liquid level control, you can use a relay to activate a motor or valve to control the level. The third circuit show this kind of application,  and the relay can be seen as liquid/water level switch. The optional resistor seen in the third circuit is an option for high voltage transient that often occurs in automotive environment, and you can omit it if  there is no such possibility. [Circuit's schematic diagram source: National Semiconductor Application Notes]

Amplitude Average Detector Circuit

This is a design circuit for sensing amplitude. This circuit is similar peak detector. But the output won’t immediately follow the input peaking. Because the output follows the input peak slowly, averaging effect will be seen at the output. This is the figure of the circuit.

This circuit is work based on two IC’s, there are LM307 and LF351. Use 1% resistor for R1, R2, R3, and R4, and you can achieve negative and positive cycle difference of 0.5dB at the worst case. If you use 5% resistors then the difference between positive and negative cycle gain difference would be about 2dB (worst case). The averaging time constant will depend on R5-C2, you can change to other values if needed. [Circuit's diagram source: National Semiconductor Application Notes].

Headphone Buffer Amp Circuit

This is a design circuit for headphone buffer amplifier. This circuit is work based on 5532 IC. This is the figure of the circuit.

The key component is the 5532 Dual Op Amp. While ordinarily this part is chosen for it's low noise characteristics, it is also capable of delivering nearly 350mW of output power per side, more than enough to drive headphones. The circuit can operate from bipolar voltages from +/-5V to +/-18V and it is not absolutely necessary that the + and - supply voltages be the same magnitude. The superior supply voltage rejection of the IC allows operation with unregulated supplies.

Dual Channel Digital Volume Control Circuit

This circuit is design for control the volume audio. This circuit for replacing your manual volume control in a stereo amplifier. This circuit is control by three IC, there are 555 timer, 74LS193, and 4066. This is the figure of the circuit.

IC1 timer 555 is configured as an astable flip-flop to provide low-frequency pulses to up/down clock input pins of pre-stable up/down counter 74LS193 (IC2) via push-to-on switches S1 and S2. To vary the pulse width of pulses from IC1, one may replace timing resistor R1 with a variable resistor. Operation of switch S1 (up) causes the binary output to increment while operation of S2 (down) causes the binary output to decrement. The maximum count being 15 (all outputs logic 1) and minimum count being 0 (all outputs logic 0), it results in maximum and minimum volume respectively.

Stepper Motor Circuit Using 74194

This is the circuit for the driver to adjust the motor speed at STEPPER motor. This circuit can drive a motor 12v to 24V. This circuit is based on 74194. The test series are placed differently and show SN7474 in logic block form and LED lights are used to indicate the motor coil is removed. This is the figure of the circuit.

STEPPER motor circuit uses IC 555 astable oscillator produces a series of clock pulses fed to Pin 11 of integrated circuit SN74194. Every time the clock pulse goes HIGH (positive) in the country in the SN74194’s HIGH OUTPUT terminal (PIN’s 12, 13, 14, 15), transferred either UP or DOWN y one place. Referring to the “Stepper Motor Driver Waveforms” diagram. Shift direction is controlled by a switch S2.

When S2 is in the middle position OFF HIGH-state output will remain in last position and the motor will be stopped. When the base of Q6 is a shift to PIN LOWER 12-15 – 14 – 13-12. When the base Q7 is a shift to PIN LOW 12 – 13 – 14 – 15 – 12. Direction of the shift pulses determine the direction of motor rotation. The pulses from the OUTPUT’s of SN74194 four segments are fed Driver ULN2003. When the input of a segment is HIGH, it will activate the Darlington transistor and OUTPUT will conduct current through one of the motor coils. As the roll motor turned ON in order to follow the motor rotates these steps.
[Circuit source: home.cogeco.ca]

Radio Collar Transmitter Circuit

This is a circuit diagram for radio transmitter suitable for installation in a series of radio transmitting collars. This circuit is work with based on 555 timer and JFET. This is the figure of the circuit.

The pulse in the FM band between 88 MHz to 105 Mhz, which can be adjusted. Ne IC 555 are cable as astable multi vibrator to produce tone.L1, C3 and Q1 form a modulator. End of Q2 to the power amplification. For inductors made of 5 rounds, he was 5 mm insulated copper wire on a standard ball pen refill. Remove the refill and making a tap on the center coil varies transmission frequency. To experiment with the number of turns. Careful!!! What might once have had to turn the tap on center. Use 50 cm long insulated copper wire as an antenna.

Part:
R1…………………………………. 10K
R2 …………………………………1 M Ohm
R3 ………………………………….330 Ohm
R4 …………………………………..1 M Ohm
R5……………………………………. 330 Ohm
R6 ……………………………………200 Ohm POT
C1 ……………………………………..0.1 uF Ceramic
C2…………………………………….. 0.01 uF Ceramic
C3…………………………………….. 13 pF Ceramic
C4, C5, C6, C7 ……………………..0.01 uF Ceramic
Q1, Q2 ………………………………..2N4392 JFET
D1 ……………………………………….1N 914 Diode
IC 1……………………………………… NE 555

Automatic Intruder Alarm Using 4011 IC

This is a design circuit for a simple zone alarm circuit. This circuit has features automatic Exit and Entry delay and a timed Bell / Siren Cut-Off. This circuit is work with controlled by IC 4011. This circuit is easy to built and used. This is the figure of the circuit.

The operation of the circuit is begin when, first, check whether buildings are safe and green LED lights. Then move SW1 to the “set” position. Red LED will light up. You now have about 30 seconds to leave the building. When you go back and open the door – the Buzzer will sound. You then have about 30 seconds to move SW1 to the “off” position. If you fail to do so – the relay will energize and the Siren will sound. While at least one of the switches in the closed loop is usually kept open – the Siren will continue to be heard. However, about 15-minutes after the loop has been restored – the relay will de-energy – the Siren will Cut-off – and the alarm will reset. Of course, you can turn the Siren off at any time by moving SW1 to the “off” position. Because of manufacturing tolerances – the right length of the delay depends on the characteristics of the actual components you’ve used in the circuit. But by changing the values of R3, R6 & R9 you can adjust the Exit, Entry and Bell Cut-off times to suit your needs. Increasing the values increases the time – and vice versa.

40 LED Bicycles Light Using 555 Timer IC

This is a design circuit for flashing bicycle light powered with four C, D or AA cells (6 volts). This circuit is work with based on 555 timer IC for controller. This is the figure of the circuit.

Two sets of 20 LEDs will alternately flash at approximately 4.7 cycles per second using RC values shown (4.7K for R1, 150K for R2 and a 1uF capacitor). Time intervals for the two lamps are about 107 milliseconds (T1, upper LEDs) and 104 milliseconds (T2 lower LEDs). Two transistors are used to provide additional current beyond the 200 mA limit of the 555 timer. A single LED is placed in series with the base of the PNP transistor so that the lower 20 LEDs turn off when the 555 output goes high during the T1 time interval. The high output level of the 555 timer is 1.7 volts less than the supply voltage. Adding the LED increases the forward voltage required for the PNP transistor to about 2.7 volts so that the 1.7 volt difference from supply to the output is insufficient to turn on the transistor.

Guitar Amplifier

Guitar amplifiers are always an interesting challenge. This is a design circuit for the guitar amplifier. The amp is rated at 100W into a 4 Ohms load, as this is typical of a "combo" type amp with two 8 Ohm speakers in parallel. There are 2 main part in this amplifier. There are pre amp and power amp.

The preamp circuit is shown in Figure 1, and has a few interesting characteristics that separate it from the "normal", assuming that there is such a thing. This is simple but elegant design, that is provides excellent tonal range. The gain structure is designed to provide a huge amount of gain, which is ideal for those guitarists who like to get that fully distorted "fat" sound.

The power amp board using TIP35/36C transistors, the output stage is deliberately massive overkill. This ensures reliability under the most arduous stage conditions. No amplifier can be made immune from everything, but this does come close. The power amp (like the previous version) is loosely based on the 60 Watt amp previously published (Project 03), but it has increased gain to match the preamp. Other modifications include the short circuit protection - the two little groups of components next to the bias diodes (D2 and D3). This new version is not massively different from the original, but has adjustable bias, and is designed to provide a "constant current" (i.e. high impedance) output to the speakers - this is achieved using R23 and R26. Note that with this arrangement, the gain will change depending on the load impedance, with lower impedances giving lower power amp gain. This is not a problem, so may safely be ignored.

Multiplexer with Limiter and Low Pass Filter

This is a design circuit for stereo encoder. This circuit is using BH1417 Stereo Encoder. This circuit using with pre-emphasis, limiter so that the music can be transmitted at the same audio level, low pass filter that blocks any audio signals above 15 KHz to prevent any RF interference and crystal based stereo encoder for stereo transmission. This is the figure of the circuit.

The BH1417 single chip IC can be supplied with 6 - 15V voltage, consumes only around 25mA while providing very sound quality and improved 40dB channel separation. The IC is only available in SOP22 IC case and this may be an inconvenience for some folks. On the other hand, because the chip is smaller than regular DIP-based ICs it is possible to fit the entire stereo coder on a small PCB. This IC is requires 7.6MHz crystal oscillator which is pretty hard to find. The good news is that you can use 7.68 MHz crystal instead. In fact our BH1417 stereo encoder prototype uses 7.68 MHz crystal. This has absolutely no effect on stereo encoding process, we have tested it and stereo sound is crystal clear.

Carrier Based Current Monitor

This circuit is utilizes AC carrier modulation techniques to meet APD current monitor requirements. This circuit features 0.4% accuracy over the sensed current range, runs from a 5V supply and has the high noise rejection characteristics of carrier based “lock in” measurements. This is the figure of the circuit.

This circuit is based on The LTC1043 that is used to switch array is clocked by its internal oscillator. Oscillator frequency, set by the capacitor at Pin 16, is about 150Hz. S1 clocking biases Q1 via level shifter Q2. Q1 chops the DC voltage across the 1kW current shunt, modulating it into a differential square wave signal which feeds A1 through 0.2mF AC coupling capacitors. A1’s single-ended output biases demodulator S2, which presents a DC output to buffer amplifier A2. A2’s output is the circuit output. Switch S3 clocks a negative output charge pump which supplies the amplifier’s V– pins, permitting output swing to (and below) zero volts. The 100k resistors at Q1 minimize its on-resistance error contribution and prevent destructive potentials from reaching A1 (and the 5V rail) if either 0.2mF capacitor fails. A2’s gain of 1.1 corrects for the slight attenuation introduced by A1’s input resistors. In practice, it may be desirable to derive the APD bias voltage regulator’s feedback signal from the indicated point, eliminating the 1kW shunt resistor’s voltage drop. [Schematic’s circuit source: Linear Technology Notes].

Trans-Impedance Amplifier for DAC Outputs Using LH4117 Single IC Chip

This is a circuit for trans-impedance amplifier that using to DAC output. This circuit is based on LF4117 that is an excellent match to amplify the output of DACs like the DAC0800. The fast settling time of 9 ns to 0.02% does not degrade the performance of the DAC. On the other hand, the DAC0800 provides complimentary current outputs, which are current sinks and do not need a fixed voltage to work accurately. This is the figure of the circuit.

The DAC0800 is fed a reference current of IREF e 2 mA into pin 14. This is achieved by the LH0070 voltage reference with 10V output. A resistance of 5 kX (R1 a R2) is connected to pin 14, which is a virtual ground, thus providing the reference current of 2 mA. The grounded pin 15 provides the reference voltage for pin 14. The DAC has eight current sinks, each set for half the current of the previous one. Through switches, controlled by the input logic levels, their open collectors are connected to one of the two outputs. The sum of the output currents I1 and I2 equals the reference current of 2 mA. Because of the open collector configuration the outputs do not have to be tied to a fixed voltage level. The outputs of the DAC0800 are connected to the inputs of the LH4117 through 100X resistors (R4 and R5). This is to decouple the inputs of the amplifier from the output capacitance of the DAC, which is typically 23 pF to 30 pF. Especially the inverting input is sensitive to capacitance. [Schematic’s circuit source: National Semiconductor Notes].

DC Coupled Current Monitor Circuit

This is design circuit for DC coupled current monitor that is eliminates the previous circuit’s trim but pulls more current from the APD bias supply. A1 floats powered by the APD bias rail. This is the figure of the circuit.

The 15V zener diode and current source Q2 ensure A1 never is exposed to destructive voltages. The 1kW current shunt’s voltage drop sets A1’s positive input potential. A1 balances its inputs by feedback controlling its negative input via Q1. As such, Q1’s source voltage equals A1’s positive input voltage and its drain current sets the voltage across its source resistor. Q1’s drain current produces a voltage drop across the ground referred 1k resistor identical to the drop across the 1kW current shunt and, hence, APD current. This relationship holds across the 20V to 90V APD bias voltage range. The 5.6V zener assures A1’s inputs are always within their common mode operating range and the 10M resistor maintains adequate zener current when APD current is at very low levels.

Two output options are shown. A2, a chopper stabilized amplifier, provides an analog output. Its output is able to swing to (and below) zero because its V– pin is supplied with a negative voltage. This potential is generated by using A2’s internal clock to activate a charge pump which, in turn, biases A2’s V– pin. A second output option substitutes an A-to-D converter, providing a serial format digital output. No V– supply is required, as the LTC2400 A-to-D will convert inputs to (and slightly below) zero volts. [Schematic’s circuit source: Linear Technology Notes].

APD Bias Supply and Current Monitor

This circuit is consists of two circuit but in the figure this circuit is combines. This is the figure of the circuit.

The programmable APD bias supply is as before, except that feedback comes via A2. A2, sensing after the 1kW current shunt, isolates the R1-R2 path loading, preventing it from influencing the shunt’s voltage drop. A2’s action also insures tight output regulation, despite the current shunt’s presence. The current monitor, measures across the 1kW current shunt, presenting its output in Q1’s drain line. As shown, the output has about 1kW output impedance, although either of the circuit output options may be employed.

When considering circuit operation, note that both amplifiers are powered by the charge pump’s high voltage output, with their V– pin returned to the “2/3 VOUT” point. This biasing permits the amplifiers to process high voltage signals, although the voltage across them never exceeds 30V.

Programmable Pressure Transducer

This circuit is design allows only a small diaphragm deflection sin it has limited elasticity, and this produces only a very small output signal, only about 1% modulation of the bridge resistance elements. This circuit is based on LM4041. This is the figure of the circuit.

The A2 circuit provides for the precision adjustment, via DCP1, of any transducer initial null offset error. To accomplish this, the bridge excitation voltage is programmable attenuated by the R2, R3, R4, R5 network and applied to DCP1. Boosting the ~10mV/psi bridge signal by 100x to a convenient 1V/psi output level is the job of the A3 non-inverting amplifier via its feedback and calibration network consisting of R7 through R9 and DCP2. The range for the zero adjustment voltage is from +22mV to –22mV. The resolution is 172uV and is proportional to the bridge excitation voltage, thus improving the temperature stability of the zero adjustment.

The net result of the combination of transducer and the Figure 4 circuitry is a signal conditioned precision pressure sensor that is compatible (thanks to DCP1 and 2) with full automation of the calibration process, is very low in total power draw (< 1 milli ampere, most of which goes to transducer excitation), and (equally important) is low in cost.

Miniature Audio Oscillator Circuit

This circuit is designed as a pocket sized high performance audio oscillator. This circuit can operated using battery operated version was possible and could be made at very low cost as well by using one quad op-amp to provide the entire active circuitry. This is the complete figure for design circuit.

In the figure, there are only two control pots (RV1 and RV2) and two DPDT switches. The output level pot includes an on-off switch and is of logarithmic taper to allow easier setting at low (i.e. millivolt) levels. This pot is directly coupled to A4's output to minimize response errors, provided that the load impedance is constant or quite high compared to the output impedance provided by Miniosc. The frequency sweep control (RV1A/B) has a range of about 24:1 and in combination with the High-Low range switch having a 18:1 ratio, the audio band is covered (with the exception of the lowest octave) in two overlapping ranges. The possibility of a single sweep of the audio band without the range switch was tried out and later dropped in preference to the present design.

Types like the TL074, TL084, LF347 and LF444 and other quad op-amps with compatible pin outs are not recommended for use due to both the increased battery drain and reduced margin of minimum operating voltage. The TL064 is alone in having operation specified down to a plus and minus 3 volt supply. [Schematic’s circuit source: Phill Allison Notes].

8 Channel LPT Relay Circuit

This is a simple design circuit and convenient way to interface 8 relays. This circuit is control using PC. This is the figure of the circuit.

This circuit is using Power Battery Terminal (PBT) for easy relay output and aux power connection. The LED on each channel indicates relay status. Berg pins for connecting power and trigger voltage.

5 – Band Graphic Equalizer Circuit

This circuit is for graphic equalizer that can build with low components count and control using LA3600 single IC chip. The internal design of the chip uses transistors gyrator circuit, with connections to external capacitors to set the response. This is the figure of the circuit.

 

Sorry, this picture is not clear. This graphic equalizer circuit is suitable for tape-recorders, radio-cassette recorders, car stereos, or home theater sound systems.

Description of external parts
C1, C2 : Capacitors used to fix fo (resonance frequency)
C2 : Input capacitor. Decreasing the capacitor value lowers the frequency response at low frequencies.
C3 : Input capacitor. Decreasing the capacitor value lowers the frequency response at low frequencies.
C4 : Decoupling capacitor. Decreasing the capacitor value makes the effect of power supply stronger, whereby ripple is liable to occur.
C5 : Power capacitor.
C6 : Output capacitor. Decreasing the capacitor value lowers the frequency response at low frequencies.

Maximum supply voltage VCC max 20V must not be exceeded. The operating voltage is in the range of 5 to 15V. [Schematic diagram source: SANYO Electric's Application Notes].