Power Supply Circuit
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12V Battery Charger for Sealed Lead Acid
2009-10-09 02:14:28
This battery charger is for 12V Seales Lead Acid (SLA) battery. It is actually a half-wave rectifier. It only charges the battery on every half cycle. The plug pack doesn't like this as it leaves residual flux in the core of the transformer and causes it to overheat. There are a number of points we need to cover about the care and use of Sealed Lead Acid batteries. Firstly, these batteries must be charged, discharged and stored very carefully. We normally think batteries can be stored for months (if not years) and they will be available for immediate use. This is not the case with SLA batteries. If you store a NEW, full charged SLA battery for 6 months or more, you will find it may be fully discharged. You may also find you cannot charge it!! It may be worthless. That's how delicate SLA batteries are. They must be charged on a regular basis to prevent them discharging to a very low voltage level. If the terminal voltage of a SLA battery is allowed to go below 8v, a process cal
2009-10-09 02:14:28
This battery charger is for 12V Seales Lead Acid (SLA) battery. It is actually a half-wave rectifier. It only charges the battery on every half cycle. The plug pack doesn't like this as it leaves residual flux in the core of the transformer and causes it to overheat. There are a number of points we need to cover about the care and use of Sealed Lead Acid batteries. Firstly, these batteries must be charged, discharged and stored very carefully. We normally think batteries can be stored for months (if not years) and they will be available for immediate use. This is not the case with SLA batteries. If you store a NEW, full charged SLA battery for 6 months or more, you will find it may be fully discharged. You may also find you cannot charge it!! It may be worthless. That's how delicate SLA batteries are. They must be charged on a regular basis to prevent them discharging to a very low voltage level. If the terminal voltage of a SLA battery is allowed to go below 8v, a process cal
Lead-Acid Batteries Charger with Solar Panel
2009-09-28 21:27:40
This Batteries Charger is intended for charging sealed lead-acid batteries with a solar panel in small and portable applications. The customary diode that prevents the battery from discharging through the solar panel has been replaced by a FET-comparator combination. The batteries charger will stop charging once a pre-set voltage (temperature compensated) has been reached, and recommence charging when the voltage has dropped off sufficiently. The load is disconnected when the battery voltage drops below 11V and reconnected when it gets back to 12.5V. Solar Batteries Charger Schematic The batteries charger circuit has the following features: Charges until Vbat = 13.8V (adjustable), then float charges; Shuts down load when Vbat < 11V (adjustable), resets at 12.5V; Temperature compensation; Will work with cheap and readily available components like LM393 comparators and BUZ11 FETs; Uses less than 0.5mA when using TLC393 comparators; Burns less than 20mW in
2009-09-28 21:27:40
This Batteries Charger is intended for charging sealed lead-acid batteries with a solar panel in small and portable applications. The customary diode that prevents the battery from discharging through the solar panel has been replaced by a FET-comparator combination. The batteries charger will stop charging once a pre-set voltage (temperature compensated) has been reached, and recommence charging when the voltage has dropped off sufficiently. The load is disconnected when the battery voltage drops below 11V and reconnected when it gets back to 12.5V. Solar Batteries Charger Schematic The batteries charger circuit has the following features: Charges until Vbat = 13.8V (adjustable), then float charges; Shuts down load when Vbat < 11V (adjustable), resets at 12.5V; Temperature compensation; Will work with cheap and readily available components like LM393 comparators and BUZ11 FETs; Uses less than 0.5mA when using TLC393 comparators; Burns less than 20mW in
Camera Battery Charger for Train Mounted
2009-09-21 10:13:40
This camera battery charger circuit will keep the battery for a train mounted camera charged and will shut the camera off after a few seconds when power is no longer applied to the track. This camera battery charger circuit is designed for DCC systems and the battery is essentially used as a capacitor as it is not allowed to become discharged. The battery also controls the voltage to the camera as any current passed through R1 that is not needed by the camera is shunted through the battery. This is an inefficient but cheap way to control the voltage. (Circuits Without Pages Of Their Own) Source: Train Mounted Camera Battery Charger
2009-09-21 10:13:40
This camera battery charger circuit will keep the battery for a train mounted camera charged and will shut the camera off after a few seconds when power is no longer applied to the track. This camera battery charger circuit is designed for DCC systems and the battery is essentially used as a capacitor as it is not allowed to become discharged. The battery also controls the voltage to the camera as any current passed through R1 that is not needed by the camera is shunted through the battery. This is an inefficient but cheap way to control the voltage. (Circuits Without Pages Of Their Own) Source: Train Mounted Camera Battery Charger
Solar-Battery Regulator-Load Controller
2009-09-12 02:54:03
This Solar-Battery regulator allows solar cell arrays to be connected to either conventional lead-acid, sealed lead-acid, or lithium storage batteries without fear of overcharging. It allows two different electrical loads to be driven from the batteries at two different charge states to maximise power usage efficiency. The existing power control circuit in this fridge aims to avoid discharging a car battery by ensuring that it only runs down to a certain voltage. This means that it will only run for a short time after the engine is turned off. While a sensible precaution, this prevents efficient use of solar power to drive it. The existing circuit also suffers from oscillation caused by voltage drops in the wiring from the unit to the power source, generally a cigarette lighter socket; Rather than switching off cleanly the load relay spends several tens of minutes clicking on and off uselessly as the car battery voltage slowly drops back from its on-charge voltage. I wanted to be a
2009-09-12 02:54:03
This Solar-Battery regulator allows solar cell arrays to be connected to either conventional lead-acid, sealed lead-acid, or lithium storage batteries without fear of overcharging. It allows two different electrical loads to be driven from the batteries at two different charge states to maximise power usage efficiency. The existing power control circuit in this fridge aims to avoid discharging a car battery by ensuring that it only runs down to a certain voltage. This means that it will only run for a short time after the engine is turned off. While a sensible precaution, this prevents efficient use of solar power to drive it. The existing circuit also suffers from oscillation caused by voltage drops in the wiring from the unit to the power source, generally a cigarette lighter socket; Rather than switching off cleanly the load relay spends several tens of minutes clicking on and off uselessly as the car battery voltage slowly drops back from its on-charge voltage. I wanted to be a
DC-DC Converter With Variable VDC Input
2009-09-12 01:34:49
A DC-DC converter or another name known as buck regulator or switching regulator (because the input voltage can be either above or below the desired voltage output), provides stable regulated output voltage to supply electronic circuits. LM2576 converter circuits perform same function as the commonly known voltage regulator LM7805 from National Semiconductor. The 7805 voltage regulator dissipates a lot heat. The higher input voltage, the more heat is generated. The extra input energy is converted to heat, keeping the output voltage regulated at 5V. LM2576 DC-DC Converter Circuits There a variety of capacitors out there in the market. Capacitance, voltage rating, dielectric material, etc... . Choose a suitable voltage rating across the capacitor. The circuits deals with high current, therefore it will be better to choose a low ESR (equivalent series resistance) Aluminum electrolytic capacitor. As a general guide, a higher voltage rating has lower ESR rating. The inductor coil use s
2009-09-12 01:34:49
A DC-DC converter or another name known as buck regulator or switching regulator (because the input voltage can be either above or below the desired voltage output), provides stable regulated output voltage to supply electronic circuits. LM2576 converter circuits perform same function as the commonly known voltage regulator LM7805 from National Semiconductor. The 7805 voltage regulator dissipates a lot heat. The higher input voltage, the more heat is generated. The extra input energy is converted to heat, keeping the output voltage regulated at 5V. LM2576 DC-DC Converter Circuits There a variety of capacitors out there in the market. Capacitance, voltage rating, dielectric material, etc... . Choose a suitable voltage rating across the capacitor. The circuits deals with high current, therefore it will be better to choose a low ESR (equivalent series resistance) Aluminum electrolytic capacitor. As a general guide, a higher voltage rating has lower ESR rating. The inductor coil use s
DC-DC Converter 12V to 120V 20W
2009-09-12 00:53:05
Here is a DC to DC Converter schematic. The design is a simple saturation-limited push-pull converter. There is no special reason to use PNP transistors. I used them simply because I had a box full of them around. You may well turn over the design to use NPN transistors. The 2SC945 is a bias switch for startup. When applying 12V power, this transistor applies enough bias to the power transistors to get the oscillation started. Soon later, the 100uF capacitor charges up, the transistor goes off, and the power transistors self-bias into cut-off, such that cross-conduction is eliminated. After removing power, the 6k8 resistor discharges the bias timing capacitor, as otherwise the circuit would be unable to restart! The secondary rectifiers are ultrafast diodes. These are NOT 1N4007! And the 220nF capacitors for the secondary filter are no typos; the diodes deliver almost pure DC, since the oscillation waveform is square, so only some noise filtering is needed. No electrolytics are nec
2009-09-12 00:53:05
Here is a DC to DC Converter schematic. The design is a simple saturation-limited push-pull converter. There is no special reason to use PNP transistors. I used them simply because I had a box full of them around. You may well turn over the design to use NPN transistors. The 2SC945 is a bias switch for startup. When applying 12V power, this transistor applies enough bias to the power transistors to get the oscillation started. Soon later, the 100uF capacitor charges up, the transistor goes off, and the power transistors self-bias into cut-off, such that cross-conduction is eliminated. After removing power, the 6k8 resistor discharges the bias timing capacitor, as otherwise the circuit would be unable to restart! The secondary rectifiers are ultrafast diodes. These are NOT 1N4007! And the 220nF capacitors for the secondary filter are no typos; the diodes deliver almost pure DC, since the oscillation waveform is square, so only some noise filtering is needed. No electrolytics are nec
12 to 28V Boost Regulator LM2585
2009-09-11 00:35:06
This boost regulator is for those times when you have a 28v relay, but want to use it with a 12v source. The circuit is built around the National Semiconductor LM2585, and uses the energy stored in an inductor to boost the 12 to 28v. Output voltage can be varied by adjusting the ratio of resistor values on the feedback pin. The voltage regulator circuit does it's switching around 100 Khz, but generates no noise if SMT components are used. Output is good for about half an amp continuous, enough to power two or three large microwave relays. The board measures 1.5"x2". It is important to note at least these three cautions before powering up the board: A short-circuit on the output will kill U1 and D1. Always use a 1 ohm 5w resistor, or a 2.5A fast fuse on the 12v input lead. Do not omit the LED (D2); It provides a visual indicator of a properly operating boost condition, but more importantly, it also provides a minimum load for the output, preventing an output "spike" which will other
2009-09-11 00:35:06
This boost regulator is for those times when you have a 28v relay, but want to use it with a 12v source. The circuit is built around the National Semiconductor LM2585, and uses the energy stored in an inductor to boost the 12 to 28v. Output voltage can be varied by adjusting the ratio of resistor values on the feedback pin. The voltage regulator circuit does it's switching around 100 Khz, but generates no noise if SMT components are used. Output is good for about half an amp continuous, enough to power two or three large microwave relays. The board measures 1.5"x2". It is important to note at least these three cautions before powering up the board: A short-circuit on the output will kill U1 and D1. Always use a 1 ohm 5w resistor, or a 2.5A fast fuse on the 12v input lead. Do not omit the LED (D2); It provides a visual indicator of a properly operating boost condition, but more importantly, it also provides a minimum load for the output, preventing an output "spike" which will other
Mini Bench Power Supply Circuit
2009-07-16 10:39:02
Every electronics engineer is familiar with the anxiety of the moment when power is first applied to a newly-built circuit, wondering whether hours of work are about to be destroyed in a puff of smoke. A high quality power supply with an adjustable current limit function is an excellent aid to steadying the nerves. Unfortunately power supplies with good regulation performance are expensive and homebrew construction is not always straightforward. Many of the "laboratory power supplies" currently on the market are low-cost units based on switching regulators which, although certainly capable of delivering high currents, have rather poor ripple performance. Large output capacitors (which, in the case of a fault, will discharge into your circuit) and voltage overshoot are other problems. The power supply described here is a simple unit, easily constructed from standard components. It is only suitable for small loads but otherwise has all the characteristics of its bigger brethren. Betwe
2009-07-16 10:39:02
Every electronics engineer is familiar with the anxiety of the moment when power is first applied to a newly-built circuit, wondering whether hours of work are about to be destroyed in a puff of smoke. A high quality power supply with an adjustable current limit function is an excellent aid to steadying the nerves. Unfortunately power supplies with good regulation performance are expensive and homebrew construction is not always straightforward. Many of the "laboratory power supplies" currently on the market are low-cost units based on switching regulators which, although certainly capable of delivering high currents, have rather poor ripple performance. Large output capacitors (which, in the case of a fault, will discharge into your circuit) and voltage overshoot are other problems. The power supply described here is a simple unit, easily constructed from standard components. It is only suitable for small loads but otherwise has all the characteristics of its bigger brethren. Betwe
DC DC Converter Circuit
2009-05-28 23:57:19
Electronic system is designed to operate from a supply voltage, which is usually assumed to be constant. A voltage regulator provides this constant DC output voltage and contains circuitry that continuously holds the output voltage at the design value regardless of changes in load current or input voltage, assuming that the load current and input voltage are within the specified operating range for that regulator. In portable systems, the input voltage is often a battery, a DC voltage. A DC-to-DC converter is a device that accepts a DC input voltage and produces a DC output voltage. Typically the output produced is at a different voltage level than the input. In addition, DC-to-DC converters are used to provide noise isolation, power bus regulation, etc. This is a summary of some of the popular DC-DC Converter Topologies When the output voltage set point is less than the input voltage, such regulator is called a Buck converter. When the output voltage set point is higher, it is a Boo
2009-05-28 23:57:19
Electronic system is designed to operate from a supply voltage, which is usually assumed to be constant. A voltage regulator provides this constant DC output voltage and contains circuitry that continuously holds the output voltage at the design value regardless of changes in load current or input voltage, assuming that the load current and input voltage are within the specified operating range for that regulator. In portable systems, the input voltage is often a battery, a DC voltage. A DC-to-DC converter is a device that accepts a DC input voltage and produces a DC output voltage. Typically the output produced is at a different voltage level than the input. In addition, DC-to-DC converters are used to provide noise isolation, power bus regulation, etc. This is a summary of some of the popular DC-DC Converter Topologies When the output voltage set point is less than the input voltage, such regulator is called a Buck converter. When the output voltage set point is higher, it is a Boo
Power Supply AC - DC 12V
2009-04-29 12:35:21
The term power supply is more commonly abbreviated to PSU, this will be used from hereon in. Telecommunications equipment is designed to operate on voltages lower than the domestic Mains voltage. In order to reduce this voltage a PSU is used. In order to power up the electronics experimental , many of electronics hobbyist have built there own 5v and 12v PSU by them self; which require a little bit of power. However, if the load requires too much amps, you have to calculate all the parameters to build a stable power supply. The main function of power supply is to convert AC to DC, the first stage is to make full wave rectifier to the AC signals by using bridge rectifier, filter the rectified wave by using filtering capacitor and finally select the appropriate voltage regulator to generate pure DC signal. To provide a useable low voltage the PSU needs to do a number of things:- * Reduce the Mains AC (Alternating current) voltage to a lower level. * Convert this lower volt
2009-04-29 12:35:21
The term power supply is more commonly abbreviated to PSU, this will be used from hereon in. Telecommunications equipment is designed to operate on voltages lower than the domestic Mains voltage. In order to reduce this voltage a PSU is used. In order to power up the electronics experimental , many of electronics hobbyist have built there own 5v and 12v PSU by them self; which require a little bit of power. However, if the load requires too much amps, you have to calculate all the parameters to build a stable power supply. The main function of power supply is to convert AC to DC, the first stage is to make full wave rectifier to the AC signals by using bridge rectifier, filter the rectified wave by using filtering capacitor and finally select the appropriate voltage regulator to generate pure DC signal. To provide a useable low voltage the PSU needs to do a number of things:- * Reduce the Mains AC (Alternating current) voltage to a lower level. * Convert this lower volt