Here’s a circuit which stimulates nerves of the part of your body exactly where electrodes are generally attached. It is useful to help remedy headache along with muscular discomfort and bring back frozen muscles that impair movement. Though it offers muscles stimulation and invigoration, it’s mostly an aid in removing cellulitis. The device comprises 2 units: muscular stimulator and also timer.

Figure 1 exhibits the circuit with the muscular stimulator. IC 7555 is actually wired just as one astable multivibrator to build about 80Hz pulses. The particular output involving IC1 is fed to be able to transistor T1, whose emitter is actually further connected to the starting of transistor T2 via R3 as well as VR1. The enthusiast of transistor T2 is connected to one end of the secondary turning of transformer X1. The opposite end on the secondary winding from the transformer is connected to ground.

As soon as IC1 oscillates, transformer X1 is actually driven with the pulse frequencies generated to create high voltage in its principal terminals. Separate electrodes are linked with each end of the primary rotating of transformer X1. Diode 1N4007 (D1) safeguards transistor T2 towards high-voltage pulses generated by the transformer.

Using potensiometer VR1 you are able to control this intensity associated with current sensing in the electrodes. The brightness level of LED1 shows the amplitude with the pulses. If you want to increase your intensity level, replace the actual 1. 8-kilo-ohm resistor along with 5. 6 kilo-ohms or higher value around 10 kilo-ohms.

X1 is really a small mains transformer along with 220V principal to 12V, 100/150mA second. It has to be reverse connected, for example, connect your secondary winding for the collector involving T2 along with ground, and key winding on the output electrodes. The productivity voltage is concerning 60V but the output current is so small there’s no danger of electric powered shock.

Electrodes are constructed with small, thinguage material plates measuring about 2. 5×2. 5 cm2 in proportions. Use accommodating wires to help solder electrodes and get connected to the output of the device. Before hanging metal electrodes to the body, wipe them having a damp cloth. After affixing the electrodes to the body (with aid from elastic bands, flip switch S1 to be able to activate your circuit along with rotate the actual knob involving intensity-control predetermined VR1 incredibly slowly until you feel a slight tingling feeling.

Figure 2 shows this timer world. It employs IC NE555 setup in monostable manner. Initially, once you press transition S2, the monostable triggers and its particular output will go high regarding 10 min’s. Thereafter, its production goes low to supply a beep sound in the piezobuzzer as well as lights the red LED (LED2) implying that excitement time is over.

Assemble the particular timer using a separate switch as well as a 9V DC battery inside same cabinet because stimulator. Tape your electrodes for the skin in opposite ends with the chosen lean muscle and move VR1 knob slowly unless you sense mild itching when the muscular excitement circuit is usually powered in. At once, flip transition S2 to get started on the timer for counting any time. At the finish of the actual timing period, the piezobuzzer beeps. Each and every session ought to last regarding 10 units.

Caution: Heart people and expectant mothers should not take advantage of this device. Additionally, do certainly not attach electrodes for you to burns, pieces, wounds or perhaps any injuries. Consult your personal doctor before by using this circuit.

Here is the circuit diagram of stereo digital volume control. This circuit could possibly be applied for upgrading your manual volume management within a stereo amplifier circuit. In this particular circuit, push-to-on switch S1 controls the forward (volume enhance) operation of the two channels while a identical switch S2 controls reverse (volume reduce) operation of the two channels.

In this digital volume control circuit, the IC1 timer 555 is set up as an astable flip-flop to deliver low-frequency pulses to up/down clock input pins of pre-setable up/down counter 74LS193 (IC2) through push-to-on switches S1 and S2. To adjust the pulse width of pulses from IC1, you may possibly replace the timing resistor R1 by using a variable resistor.

Operation of switch S1 (up) triggers the binary output to increment while operation of S2 (down) triggers the binary output to decrement. The highest count being 15 (all outputs logic 1) and lowest count being 0 (all outputs logic 0), it outcomes in highest and lowest volume respectively.

The active high outputs A, B, C and D of the counter are utilized for controlling two quad bi-polar analogue switches in each of the two CD4066 ICs (IC3 and IC4). The two of the output bits, when high, short a part of the resistor network comprising series resistors R6 thru R9 for one channel and R10 thru R13 for the other channel, and thus manage the output of the audio signals being fed towards the inputs of stereo amplifier circuit module. Push-to-on switch S3 is utilized for resetting the output of counter to 0000, and thus turning the volume of both of those channels to the lowest level.

The above diagram is a hierachical priority encoder circuit. Described on wikipedia, priority encoder is a electronic circuit or algorithm that compresses multiple binary inputs into a smaller number of outputs. The output of a priority encoder is the binary representation of the ordinal number starting from zero of the most significant input bit. They are often used to control interrupt requests by acting on the highest priority request.”

Anormal priority encoder encodes only the highest-order data line. But in many situations, not only the highest but the second-highest priority information is also needed. The circuit presented here encodes both the highest-priority information as well as the second-highest priority information of an 8-line incoming data. The circuit uses the standard octal priority encoder 74148 that is an 8-line-to-3-line (4-2-1) binary encoder with active-‘low’ data inputs and outputs.

The first encoder (IC1) generates the highest-priority value, say, F. The active ‘low’ output (A0, A1, A2) of IC1 is inverted by gates N9 through N11 and fed to a 3-line-to-8-line decoder (74138) that requires active-‘high’ inputs. The decoded outputs are active-‘low’. The decoder identifies the highest-priority data line and that data value is cancelled using XNOR gates (N1 through N8) to retain the second-highest priority value that is generated by the second encoder.

To understand the logic, let the incoming data lines be denoted as L0 to L7. Lp is the highest-priority line (active-‘low’) and Lq the second-highest priority line (active-‘low’). Thus Lp=0 and Lq=0. All lines above Lp and also between Lp and Lq (denoted as Lj) are at logic 1. All lines below Lq logic state are irrelevant, i.e. ‘don’t care’. Here p is the highest-priority value and q the second-highest-priority value. (Obviously, q has to be lower than p, and the minimum possible value for p is taken as ‘1’.)

Priority encoder IC1 generates binary output F2, F1, F0, which represents the value of p in active-‘low’ format. The complemented F2, F1, and F0 are applied to 3-line-to-8-line (one out of eight outputs is active-‘low’) decoder 74138. Let the output lines of 74138 be denoted as M0 through M7. Now only one line is active-‘low’ among M0 through M7, and that is Mp (where the value of p is explained as above). Therefore the logic level of line Mp is ‘0’ and that of all other M lines ‘1’.

The highest-priority line is cancelled using eight XNOR gates as shown in the figure. Let the output lines from XNOR gates be N0 through N7. Consider inputs Lp and Mp of the corresponding XNOR gate. Since Mp = 0 and also Lp = 0, the output of this XNOR gate is Np = complement of Lp = 1. All other L’s are not changed because the corresponding M’s are all 1’s. Thus data lines N0 through N7 are same as L0 through L7, except that the highest-priority level in L0 through L7 is cancelled in N0 through N7.

The highest-priority level in N0 through N7 is the second-highest priority leftover from L0 through L7, i.e. Nq=0 and Nj=1 for q to priority encoder 2 (IC3) to generate S2, S1, S0, which represent q. Thus the second-highest priority value is extracted. Through cascading one can recover the third-highest priority, and so on.

For example, let L0 through L7 = X X X 0 1 1 0 1. Here the highest ‘0’ line is L6 and the next highest is L3 (X denotes ‘don’t care’). Thus p=6 and q=3. Now the active-‘low’ output of the first priority encoder will be F2 F1 F0 = 0 0 1. The input to 74138 is 1 1 0 and it outputs M0 through M7 = 1 1 1 1 1 1 0 1. Since M6=0, only L6 is complemented by XNOR gates.

Thus the outputs of XNORs are N0 through N7 = X X X 0 1 1 1 1. Now N3=0 and the highest priority for ‘N’ is 3. This value is recovered by priority encoder 2 (IC3) as S2 S1 S0 = 1 0 0.

Here the simple traffic light controller which is could be used to educate kids rudiments of traffic light guidelines. The circuit utilizes easily available electronic parts. It generally consists of rectifier diodes (1N4001), a 5V regulator 7805, two timers circuit using IC 555, two relays (5V, single-changeover), three 15W, 230V light bulbs and also several discrete parts.

Mains electrical power is stepped down by transformer X1 to provide a secondary output voltage of 9V, 300 mA – AC. Then the transformer output current is rectified by a full-wave bridge rectifier composed of diodes D1 through D4, filtered by capacitor C1 and also regulated by IC 7805 (IC1).

IC2 is wired as a multivibrator with ‘on’ and ‘off’ periods of about 30 seconds each with the part values determined. Once mains power switch is turned on, pin 3 of IC2 goes high for 30 seconds. This, in turn, energises relay RL1 via transistor T1 and the red bulb (B1) glows through its normally-open (N/O) contact. At the same time, mains power is turned off from the pole of relay RL2.

As the ‘on’ time of IC2 ends, a triggers IC3 through C5. IC3 is set up as a monostable with ‘on’ time of about 4 seconds, which indicates pin 3 of IC3 will stay high for this period of time and energise relay RL2 through driver transistor T2. The amber bulb (B2) thus lightings up for 4 seconds.

Immediately after 4-second time period of timer IC3 at pin 3 lapses, relay RL2 de-energises and also the green bulb (B3) lights up for the rest of ‘off’ period of IC2, which is about 26 seconds. The green bulb is turned on through the normally closed (N/C) contacts of relay RL2.

So when mains electrical switch is turned on, red light will light up for 30 seconds, amber for 4 seconds and green for 26 seconds.

You can easily build this circuit on a general purpose PCB and enclose in a protected box. The box needs to have sufficient area for installing transformer X1 and also two relays. It could be installed near 230V AC, 50Hz power supply or mounted on the PVC tube applied in assembly of the traffic light box.

Design of the traffic light container box is demonstrated in following image:

A stout cardboard box of 30x15x10cm3 is needed for housing the lights. To make certain durability, work with a 10x45cm2 plywood plate having 1.5 centimeters thickness and also secure onto it three light outlets and the box utilizing nuts and bolts or screws.

Make three tubes of thin aluminium sheet, which is easily offered in equipment stores. The inner diameter of aluminium tubes ought to be such that these can well match on the light outlets. Working with a sharp knife, make holes opposite the outlets carefully. Wire the outlets at the back and take the cables out through the PVC tube.

To begin with, fix three 15W light bulbs (B1 through B3) and then press on the tubes. Support the other ends of the tubes in the holes made on the front panel of cardboard box. Sandwich gelatine papers of the three colors in between two sheets of cardboard and fix over the tubes. The visibility of red, amber and also green lights enhances with their installation on the tubular shape.

Simple traffic light controller circuit diagram

Here the notebook anti theft protector circuit to secure your important netbook / notebook from stealing. Basically, this is a mini security alarm generator. Fixed inside the notebook case, it will definitely sound a noisy alarm when a person attempts to grab the notebook. This very sensitive circuit utilizes a homemade tilt switch to turn on the alarm system through tilting of the laptop computer case.

The circuit utilizes readily available parts and also can easily be constructed on a little piece of general-purpose PCB or a Vero board. This circuit is operated by a 12V miniature battery applied in remote control devices.

IC TLO71 (IC1) is utilized as a voltage comparator with a potential divider composed of R2 and R3 delivering fifty percent power supply voltage at the non-inverting input (pin 3) of IC1. The inverting input gets a higher voltage through a water-activated tilt switch only when the probes in the tilt switch make contact with water. When the tilt switch is maintained in the horizontal position, the inverting input of IC1 receives a higher voltage than its noninverting input and the output continues to be low.

The CD4538 (IC2) is utilized as a monostable multivibrator with timing factors R5 and C1. Considering the shown values, the output of IC2 continues to be low for a duration of three minutes. CD4538 is an accuracy monostable multivibrator free from incorrect triggering and also is much more reliable compared to the well-known timer IC 555. Its output comes to be high when power is turned on and it gets low when the trigger input (pin 5) receives a low to high transition pulse.

The circuit device is fixed inside the notebook case in horizontal position. In this position, water inside the tilt switch properly shorts the contacts, so the output of IC1 continues to be low. The alarm system generator stays silent in the standby mode as trigger pin 5 of IC2 is low. When a person attempts to grab the notebook case, the unit takes the vertical position and the tilt switch breaks the electrical contact between the probes. Instantly the output of IC1 comes to be high and monostable IC2 is triggered. The low output from IC2 triggers the PNP transistor (T1) and then the buzzer starts beeping.

Construct the circuit as compactly as feasible so as to make the unit matchbox dimension. Make the tilt switch working with a small (2.5 centimeters long and 1cm wide) plastic bottle with two stainless pins as contacts. Fill two-third of the bottle with water such that the contacts never make electrical path when the tilt switch is in vertical position. Make sure the bottle is leakproof with adhesive or wax.

Fix the tilt switch inside the enclosure of the circuit in horizontal position. Fit the unit inside the notebook case in horizontal position working with adhesive. Work with a miniature buzzer and a micro switch (S1) for making the device small and lightweight. Maintain the notebook case in horizontal position and turn on the circuit. Your notebook is right now secured.

Here the SW transmitter circuit based on IC BEL1895. This particular transmitter circuit works in shortwave HF band (6 MHz to 15 MHz), and can be applied for shortrange communication and for educational purposes.

The circuit is composed of a mic amplifier circuit, a variable frequency oscillator, and modulation amplifier stages. Transistor T1 (BF195) is put to use as a simple RF oscillator. Resistors R6 and R7 determine base bias, while resistor R9 is utilized for stability. Feedback is provided by 150pF capacitor C11 to maintain oscillations. The primary of shortwave oscillator coil and variable condenser VC1 (365pF, 1/2J gang) form the frequency determining network.

By altering the coil inductance or the capacitance of gang condenser, the frequency of oscillation can be modified. The carrier RF signal from the oscillator is inductively coupled through the secondary of transformer X1 to the next RF amplifier-cum-modulation stage assembled around transistor T2 that is run in class ‘A’ mode. Audio signal from the audio amplifier assembled around IC BEL1895 is coupled to the emitter of transistor 2N2222 (T2) for RF modulation.

IC BEL1895 is a monolithic audio power amplifier intendeded for sensitive AM radio applications. It can deliver 1W power to 4 ohms at 9V power supply, with low distortion and noise characteristics. Since the amplifier’s voltage gain is of the order of 600, the signal from condenser mic can be straightly linked to its input without any amplification.

The transmitter’s stability is managed by the quality of the tuned circuit parts as well as the degree of regulation of the supply voltage. A 9V regulated power source is required. RF output to the aerial consists of harmonics, because transistor T2 doesn’t have tuned coil in its collector circuit. However, for short-range communication, it does not create any trouble. The harmonic content of the output may be lowered by means of a high-Q L-C filter or resonant L-C traps tuned to each of the prominent harmonics. The power output of this transmitter is about 100 milliwatts.

A really good number of circuits which shut down the power to the load on mains failure have definitely currently shown up in EFY. This circuit is different compared to other similar circuits since it consumes no electrical power when the load is off. Further, the circuit is totally solidstate as it does not utilize any sort of relay or many other electromechanical equipments.

In this circuit, the resistor R1, diode D1, capacitor C1 and also zener D2 are utilized to develop a mains-derived 9V DC source which can be fed to the triac gate. Switches S1 as well as S2 are utilized to execute “off” and also “on” operations respectively.

When S2 switch is immediately depressed, the neutral line obtains extended to MT1 of triac TR1. This in turn makes the DC voltage accessible to the transistor circuit. Capacitor C2 and also resistor R5 give the initial base drive to transistor T2 at power-on. By the time capacitor C2 is totally charged, transistor T1 is driven into saturation by means of transistor T2 and resistor R3.

The collector pin of transistor T1 is joined to the base of transistor T2 with resistor R4, and collector of transistor T2 is joined to base of transistor T1 through resistor R3, that is, there exists a shared symbiosis in between transistors T1 as well as T2. As long as transistor T1 is on, it offers the essential fence existing to the triac via resistor R7. Capacitor C3 prevents phony affair of the circuit.

The lots can be turned off either by pushing switch S1 or by shutting down the power to the circuit. When switch S1 is pressed, transistor T1 is no more in saturation and also therefore it shuts down the triac and also the tons. Because the rectifier circuit may not get line when the triac is off, it consumes positively no power when the bunch is off.

The idea can be accordingly adopted for cooking timer applications where the power to the cooking timer circuit should be shut off after the series time delay. An opto-coupler is able to change switch S1 for making use of the outcome of a low-voltage command circuit for turning off.

This is the door bell circuit with flashing LEDs to make the circuit more attractive. IC1 (NE555) is applied right here as being a clock generator. It is actually set up as an astable multivibrator whose frequency could be altered using the support of potensiometer VR1. The clock pulses received from IC1 are fed to pin 14 of IC2 (CD4017) that is a popular decade counter circuit module.

In this door bell circuit with flashing LEDs, the LEDs are connected in a rather different way. The LEDs flash sequentially from Q0 to Q9. The five trimmers of 100k each are joined to each pair of LEDs.

The IC3 is working as tune generator and then the Darlington set composed of transistors BC547B and SL100B is applied to boost its output so the circuit able to drive the loudspeaker. The frequency of IC3 is altered by potensiometer VR2. Each 100k trimmer (VR3 thru VR7) is fine-tuned to get a various tune based on personal decision. The 10 LEDs display is set up in this kind of a way that the first vertical column has orange LED1 through LED5 and then the second parallel column has green LED10 through LED6, as shown in the above circuit.

The circuit could very well be effortlessly constructed on a veroboard. Any good filtered 9V, 250mA DC power source is appropriate. Primary of the supply transformer may be joined towards the bell AC outlet factors.

Above schematic diagram is the circuit of the variable desktop power supply. Regulator IC LM317T is set up in its standard application. Diode D1 protects against polarity reversal and capacitor C1 is an additional buffer. The green LED (LED1) signifies the status of the power input. Diode D2 keeps the output voltage from increasing above the input voltage when a capacitive or inductive load is hooked up at the output. Similarly, capacitor C3 eliminates any residual ripple.

Connect a common digital voltmeter in parallel with the output leads to precisely set the wanted voltage with the support of variable resistor / potensiometer VR1. It is possible to also work with your digital multimeter in case the digital voltmeter isn’t around. Switch on S1 and set the needed voltage through potensiometer VR1 and start reading it on the digital voltmeter. Now the power supply is all set to be used.

The circuit could be built on a general purposed Printed Circuit Board (PCB). Refer refer to the following picture for the pin configuration of LM317, just before soldering it on the PCB.

When the circuit already build, then enclose the circuit inside a metallic box, the suggested power supply box shown below:

Then open up the case of the desktop computer and hook up the input line of is circuit to a free available (hanging) four-pin drive power connector of the SMPS properly.

Here the circuit diagram of musical bell with touch switch and timer. This circuit is designed around CMOS IC CD4011 which work as the delay timer and IC UM66 which is well-known musical sound generator. When touch plates are bridged (touched) by hand for a moment, the circuit will start to produce music sound. Just after a short period (few seconds), the musical sound from this circuit will automatically stop.

The highest value of power source voltage for this particular circuit is +5 volts. The IC UM66 is unable to work over 3.3V voltage. IC 7805 regulator based power supply can certainly be applied to power this circuit.

Time delay can be adjusted by modifying the values of resistor R2 and capacitor C1. Three silicon diodes joined in series between pin 2 of UM66 IC and positive 5-volt rail maintain voltage carried out to pin 2 of UM66 less than 3.2 volts considering the decrease of about 1.8 volts across them.

Assemble the circuit and enclose into the plastic case. It suggested that the 5V regulated power supply also made and built in the case. Create some holes for switch, loudspeaker, mains power cable and port to the touch plate. Good luck…