Showing posts with label voltage. Show all posts
Showing posts with label voltage. Show all posts
Wednesday, September 24, 2014
Generating Stepped Voltage Circuit Diagram
This circuit converts an enter sign into one that may be composed of a number of discrete steps but which re- mains in a different way identical to the enter sign, because the steps are of equivalent peak, the harmonic con- tent of the output sign shall be dependent upon the amplitude of the enter sign.
This characteristic is very useful within the making of electronic tune.
The circuit uses quantitised pulse-width modulation for the including of the step-formed enters sign. Pulse-width modulation is acquired by comparing a triangular voltage with the analogue enter sign by the use of a comparator; the quantitising, that may be the including of the steps, takes place by replacing the triangular voltage with a stepped voltage. The transistor transfers the rate on C2 to capacitor C4.
Throughout the following part cycle C2 is rerated by means of Dl. ln this manner the voltage across C4 increases in discrete steps, the height of the steps being deter- mined by the ratio C2:4. Whilst the voltage across C4 rises above a certain price, N2 switches transistor T2 on by means of gate N3 and disrates capacitor C4. Whilst the capacitor is completely disrated, N2 switches off T2 and C4 continues to rate again in discrete steps. The stepped voltage uses to the inverting enter of lC2 which is l hooked up as a comparator. Low- move clear out R4/C7 within the output of lC2 converts the heartbeat-width modulated sign again to an analogue one. The d.c. voltage degree at the non- inverting enter uses by potentiometer P2 to part the significance of the stepped voltage. The environment of P1 depends on the enter sign which should be attenuated such that the maximum price at the slider of Pl is at all times smaller than i the utmost price of the stepped I voltage. The collection of steps can also be decided on by various the worth of C4. lt is imaginable to use a varicap in preference to C4 with the varicap voltage being managed by the tune program or the enter sign. Attention grabbing and person results can also be acquired on this method.
This characteristic is very useful within the making of electronic tune.
Throughout the following part cycle C2 is rerated by means of Dl. ln this manner the voltage across C4 increases in discrete steps, the height of the steps being deter- mined by the ratio C2:4. Whilst the voltage across C4 rises above a certain price, N2 switches transistor T2 on by means of gate N3 and disrates capacitor C4. Whilst the capacitor is completely disrated, N2 switches off T2 and C4 continues to rate again in discrete steps. The stepped voltage uses to the inverting enter of lC2 which is l hooked up as a comparator. Low- move clear out R4/C7 within the output of lC2 converts the heartbeat-width modulated sign again to an analogue one. The d.c. voltage degree at the non- inverting enter uses by potentiometer P2 to part the significance of the stepped voltage. The environment of P1 depends on the enter sign which should be attenuated such that the maximum price at the slider of Pl is at all times smaller than i the utmost price of the stepped I voltage. The collection of steps can also be decided on by various the worth of C4. lt is imaginable to use a varicap in preference to C4 with the varicap voltage being managed by the tune program or the enter sign. Attention grabbing and person results can also be acquired on this method.
Friday, June 6, 2014
1 5V Battery to 5V Voltage Converter Circuit Diagram
This is a Simple 1.5V Battery to 5V Voltage Converter Circuit Diagram. Stable and secure 5V DC (at 200mA max) from an ordinary 1.5V AA sized cell. At the heart of this circuit is IC1 MAX756 from Maxim, which is a CMOS step-up DC-DC switching regulator for small, low input voltage or battery-powered systems.
Simple 1.5V Battery to 5V Voltage Converter Circuit Diagram
MAX756 accepts a positive input voltage down to 0.7V and converts it to a higher pin selectable output voltage of 5V (or 3.3V). Typical full-load efficiency for the this IC is greater than 87%. Max756 combine a switch-mode regulator with an N-channel MOSFET, precision voltage reference, and power-fail detector in a single monolithic device. The MOSFET is a “sense-FET” type for best efficiency, and has a very low gate threshold voltage to ensure start-up under low-battery voltage conditions (1.1V typ).
The circuit can be easily wired on a very small rectangular common PCB.All connections should be kept as short as possible. If available,try to add a good quality 8 pin DIP socket for IC1. Note that the power inductor’s (L1) DC resistance significantly affects efficiency. For highest efficiency, limit L1’s DC resistance to 0.03 Ohm or less. A thru-hole type standard power inductor can be used. Similarly, the ESR of all capacitors (bypass and filter) affects circuit efficiency. Best performance is obtained by using specialized low-ESR capacitors.
Wednesday, December 18, 2013
Solar Cell Voltage Regulator
This device is designed to be a simple, inexpensive ‘comparator’, intended for use in a solar cell power supply setup where a quick ‘too low’ or ‘just right’ voltage indicator is needed. The circuit consists only of one 5V regulator, two transistors, two LEDs, five resistors, two capacitors, and one small battery. Although a 4-V battery is indicated, 4.5 V (3 alkalines in series) or 3.6 V (3 NiCd cells in series) will also work.
The specifications of voltage regulator IC1 are mainly determined by the size and number of the solar cells and the current pull of the equipment connected to the output. Here the low-drop 4805 is suggested but other regulators may work equally well as long as you observe the output voltage of the solar cells. Transistors T1 and T2 are complementary types i.e. one each of the pnp and npn variety.
Circuit diagram:
Although the ubiquitous BC557B (pnp) and BC547B (npn) are indicated, any small-signal equivalents out of the junk box will probably do. The values of voltage dividers R1/R6 and R3/R4 may need to be adjusted according to the type of transistor and its gain, or according to the desired voltage thresholds. Using the resistor values shown in the schematic, LED D2 turns on fully when the voltage is just above 5 volts.
LED D1 turns on when the voltage drops below 4.2 volts or so. Between those two thresholds, there is a sort of no man’s land where both LEDs are on dimly. A buzzer or other warning device could be connected across the terminals of LED D1 to give a more substantial warning if the voltage drops below operating limits. The current consumption of the circuit is about 20 mA at 5 V, and it decreases with the voltage supplied by the solar cells.
Continue reading...
The specifications of voltage regulator IC1 are mainly determined by the size and number of the solar cells and the current pull of the equipment connected to the output. Here the low-drop 4805 is suggested but other regulators may work equally well as long as you observe the output voltage of the solar cells. Transistors T1 and T2 are complementary types i.e. one each of the pnp and npn variety.
Circuit diagram:
Solar Cell Voltage Regulator Circuit Diagram
Although the ubiquitous BC557B (pnp) and BC547B (npn) are indicated, any small-signal equivalents out of the junk box will probably do. The values of voltage dividers R1/R6 and R3/R4 may need to be adjusted according to the type of transistor and its gain, or according to the desired voltage thresholds. Using the resistor values shown in the schematic, LED D2 turns on fully when the voltage is just above 5 volts.
LED D1 turns on when the voltage drops below 4.2 volts or so. Between those two thresholds, there is a sort of no man’s land where both LEDs are on dimly. A buzzer or other warning device could be connected across the terminals of LED D1 to give a more substantial warning if the voltage drops below operating limits. The current consumption of the circuit is about 20 mA at 5 V, and it decreases with the voltage supplied by the solar cells.
Reuben Posthuma
Sunday, September 29, 2013
Nicad Battery Charger Uses Voltage Cut Out
This circuit charges two NiCad cells with a constant current and features dual charging rates, voltage cutoff and an audible alarm. The circuit is powered by a 12VAC centre-tapped mains transformer, together with two rectifier diodes (D1 & D2) and a 1000mF filter capacitor. A 7806 3-terminal regulator is used to generate a 6V rail for the remainder of the circuit. Transistor Q1 and LED1 constitute a basic constant-current source. The forward voltage of the red LED (about 1.5V) minus Q1’s base-emitter voltage (about 0.6V) appears across the 6.8W or 15W emitter resistors, depending on the position of S1. With a 15W resistance in the emitter circuit, the charging current is about 60mA, whereas with 6.8W it is about 130mA.
This is sufficient to charge 600mAH "AA" cells in 14 hours and five hours, respectively. An LM393 voltage comparator (IC1) is used for the voltage cutoff function. Its inverting input is set to 2.9V (nominal) via trimpot VR1, while the non-inverting input senses battery voltage. This means that while the cells are being charged, the output transistor (in the LM393) is switched on, also switching on Q1 and enabling the current source. Once the cells are charged to approximately 80% or more of capacity, their terminal voltages will exceed 1.45V, so the voltage at the non-inverting input (pin 3) of IC1 will exceed the reference voltage on the inverting input (pin 2).
This causes IC1’s output to switch off, in turn switching Q1 off and disabling the current source. To prevent rapid switching action around the voltage cutoff point, a 100nF capacitor provides feedback between the output and inverting input of the comparator. Four NAND gates are used to build two simple oscillators of different frequencies. When cascaded together, the result is a pulsed tone from the piezo transducer to indicate charge completion.
Editors note:
Absolute terminal voltage is not always a reliable indicator of Nicad battery charge state. Importantly, batteries should never be charged for longer than the manufacturer’s specified period.
Continue reading...
This is sufficient to charge 600mAH "AA" cells in 14 hours and five hours, respectively. An LM393 voltage comparator (IC1) is used for the voltage cutoff function. Its inverting input is set to 2.9V (nominal) via trimpot VR1, while the non-inverting input senses battery voltage. This means that while the cells are being charged, the output transistor (in the LM393) is switched on, also switching on Q1 and enabling the current source. Once the cells are charged to approximately 80% or more of capacity, their terminal voltages will exceed 1.45V, so the voltage at the non-inverting input (pin 3) of IC1 will exceed the reference voltage on the inverting input (pin 2).
This causes IC1’s output to switch off, in turn switching Q1 off and disabling the current source. To prevent rapid switching action around the voltage cutoff point, a 100nF capacitor provides feedback between the output and inverting input of the comparator. Four NAND gates are used to build two simple oscillators of different frequencies. When cascaded together, the result is a pulsed tone from the piezo transducer to indicate charge completion.
Editors note:
Absolute terminal voltage is not always a reliable indicator of Nicad battery charge state. Importantly, batteries should never be charged for longer than the manufacturer’s specified period.
Thursday, September 12, 2013
Urg Negative Output from Positive Input Voltage
There are some applications, such as double-ended sensors and audio amplifiers that require a negative voltage for operation. With limited space on today’s system boards, creating a dedicated negative supply rail would add to the cost and space of the PCB. Hence, it makes sense to generate the required negative voltage from existing positive supply rails in the system.
One such solution using a traditional synchronous step-down regulator is provided by Texas Instruments in an application note entitled “Creating an Inverting Power Supply Using a Synchronous Step-Down Regulator”1. It shows you how to generate a negative voltage from a positive input voltage to the synchronous buck regulator.
Monday, September 2, 2013
Network Voltage Indicator
Using this schematic can be made a network voltage indicator electronic circuit. If the input voltage is present across the network, the optocoupler transistor is open, T1 is blocked and controlled rectifier, Th1, is in a state of conduction. Since both terminals of the piezoelectric buzzer is at the same potential, buzzer is off. If voltage disappears, the transistor T1 enters the conduction and thus makes the terminal of buzzer to be put on the ground (maintains thyristor conduction state).
Network Voltage Indicator Circuit diagram:
In this situation, there is a sufficiently large potential difference across the buzzer and D5s to determine that these two elements to indicate AC power loss, both audible and visual. By pressing the reset button current is interrupted by Th1, so thyristor enter in blocking state and the other terminal of the buzzer is connected to ground.
Network Voltage Indicator Circuit diagram:
In this situation, there is a sufficiently large potential difference across the buzzer and D5s to determine that these two elements to indicate AC power loss, both audible and visual. By pressing the reset button current is interrupted by Th1, so thyristor enter in blocking state and the other terminal of the buzzer is connected to ground.
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