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Thursday, October 7, 2010

Relay Toggle Circuit Using a 555 Timer

This 555 timer circuit below toggles a relay when a button is pressed. Pins 2 and 6, the threshold and trigger inputs, are held at 1/2 the supply voltage by the two 10K resistors. When the output is high, the capacitor charges through the 100K resistor, and discharges when the output is low. When the button is pressed, the capacitor voltage is applied to pins 2 and 6 which causes the output to change to the opposite state. When the button is released, the capacitor will charge or discharge to the new level at the output (pin 3). The parts are not critical, the resistors can be somewhat higher or lower, but the 2 resistors at pins 2 and 6 should be equal values, and the resistor connected to the cap should be 10 times greater or more.
Advantages of this circuit are the large hystersis range at the input which avoids false triggering, and only a few parts are needed for construction. One disadvantage is the relay may be engaged when power is first applied. To solve this problem, you could tie the reset line (pin 4) to another resistor/capacitor combination with the capacitor at ground and the resistor at the +V point. This will cause pin 4 to be held near ground for a short period which will reset the output when power is applied. The 100 ohm resistor and 100uF capacitor serve to filter noise on the supply line if the circuit is used in a automotive application. They may not be necessary. The circuit may work well without those parts.


2 Transistor FM Transmitter

Take care with transmitter circuits. It is illegal in most countries to operate radio transmitters without a license. Although only low power this circuit may be tuned to operate over the range 87-108MHz with a range of 20 or 30 metres.

Adjustable voltage output control by 2SC458

This again the one circuit that use in fining value output voltage, for apply give straight with the requirement of load be the circuit that is simple and have no result temperature way of the joint junction of transistor. Vout control 0V-30V at 0.1A The principle works be transistor Q1 2SC458 that built model common-emitter amplifier, which perform fine decrease input voltage get down then heal volt that give may but at collector voltage compare with ground. Which get from the combination of voltage at base – emitter pin (0.6V) with VZener diode (6.2V) already fine the value of a resister can fine the value VR1 help transistor part Q2 2SC458 perform be compared as power supply current source and current that fixed. By current at flow come in the way base pin of Q2 and when Q2 bias current. That already Voltage output get, with fining that a resister VR1 during 5.8V-15.8V. By have R3 and C1 perform be RC Filter caution. This circuit power current source get 100mA topmost should apply to load that use current low.

Adjustment power supply values 1.25-15V Max current 0.5 amp

This is power supply that have Voltage output fine the value has 1.25-15V. From by Output current that be valuable about 0.5 amp that 12V and 0.2 amp that 15V.
When Volt , from 220V houses reach transformer. It will modify Volt 220V to be 18VAC already to change rectifier circuit. Which D1, D2, C1 and R1 wasp be Full wave rectifier circuit. For modify DCV to ACV to a signal DCV. It make get a signal DCV that have voltage at pin 3 of IC1 be 20V. From that time DCV signal this reach fight DC Regulator circuit. Which use IC number LM317. This circuit will perform to maintain one’s position Voltage smoothly. Which level output voltage at get this will go out the way pin 2 of IC1. By have capacitors C2 be voltage filter in order that voltage output level of the circuit is will high class modify to follow fining. The performing fee withstands VR1 there.

3-30V 3A Adjustable Regulated DC Power Supply

This power supply is meant as an auxiliary or as a permanent power supply for all common circuits based on a stabilized DC voltage between 3 and 30V provided that the consumption does not exceed 3A. Of course this power supply unit can also be used for other purposes. Be replacing the trimmer by a potentiometer, it may even be used as an adjustable power supply unit. A good quality heatsink must be used.
Parts list:
R1 = 8.2K
R2 = 2.2K
R3 = 680R
R4 = 1K
R5 = 82K
R6 = 0.18R/5W
C1 = 470p
C2 = 100nF-63V
C3 = 100nF-63V
C4 = 100uF-63V
C5 = 10KuF-60V
D1-D6 = 6.6A
Q1 = MJ3001 (Darligton)
IC1 = UA723D
* Overload protected
* Sshort-circuit stable
* Output current: max. 3A
* Output ripple voltage: 0.5mV
* Output voltage: adjustable from 3 to 30V, stabilized
* Input voltage: 9 to 30V AC (depending on the desired output voltage)

12V Regulated Inverter Supply

When running 12V electronic devices from lead-acid battery banks, the voltage to the appliance can vary from below 11V with discharged batteries, to well above 14V during charging. Many appliances will not tolerate such a wide fluctuation and may perform poorly or be damaged.

This step-up inverter, combined with a 12V fixed regulator, is a good solution. Q1 & Q2, together with the ferrite pot-core transformer, comprise a DC-to-AC inverter. The turns ratio steps down the input voltage by about 30%. The square wave output voltage is rectified and added to the input DC voltage. The stepped up DC is then fed to a 7812 12V regulator (REG1).

MJ2955 Switching Power Supply 12V 10Amp

The switching power supply provides 12 volts, at 10 amps, maximum, using a discrete transistor regulator with an op-amp functioning as a comparator in the feedback circuit.
With reference to the schematic, the front panel power-on light is not shown. There is no adjustable current limiter in this unit, although R1, R2, R3, Q2, R8, R9, C5 and Q4 set the current limit to approximately 10 amps. As you can see, the design is very similar to that of a linear power supply, except that L1, and D1 have been added, and U1 operates in a switching mode as a comparator with a small amount of hystersis. The switching frequency of this unit varies with the output current drawn by the load. This is an undesireable feature, which is why PWM regulators are used today. With a PWM regulator, the switching frequency is constant and will produce spurs only at known discrete frequencies rather than spurs at all frequencies. The Darlington-connected pass transistor block in the schematic is there twice (in parallel) for robustness. R4 in an internal trim-pot that can set the output voltage anywhere between 5 to 15 volts.

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10A Variable Regulator power supply with LM350

This entry was posted on Wednesday, October 1st, 2008 at 8:08 am and is filed under High Current supply, dc voltage variable. You can follow any responses to this entry through the RSS 2.0 feed. Responses are currently closed, but you can trackback from your own site. This be Variable Regulator power supply Circuit. That be High Current Source 10amp. By use the integrated circuit LM350. Which usual it controls Voltage output get 1.2V to 25V and give current about 3Amp. But when bring parallel 3 pcs. Can give current output be 10Amp max for this circuit. It can adjustable voltage output get 4.5V to 25V at 10Amp.