Position: Home > Circuit Diagram > power supply circuit > Index 15
Low Cost Custom Prototype PCB Manufacturer

power supply circuit

Index 15



Simple Micro Ampere Meter Circuit

Published:2013/12/1 20:25:00 Author:lynne | Keyword: Simple Micro Ampere Meter Circuit

Simple Micro Ampere Meter Circuit
This simple micro ampere meter circuit can help in measuring small currents in five ranges: from 1 µA to 10 mA. The meter is working in this way: the current being measured Ix shifts the input voltage resulting to an output voltage with an inverted polarity. The output voltage of the opamp CA3130 is proportional to the measured current Ix.By selecting the proper feedback resistors through S1, the output voltage by full meter deflection is 1 volt in all measuring ranges. The value of the series resistor R must be selected for the particular meter being used. For example if a 1 mA meter is used, the total resistance (the sum of the resistor R and the coil resistance Ri of the meter) must be 1kΩ. If a 100 µA meter is used, the total resistance must be 100 kΩ. If needed, a potentiometer can be used for the R. Micro ampere measurement circuit schematic   (View)

View full Circuit Diagram | Comments | Reading(761)

Battery Charger Circuit, 12V

Published:2013/11/26 20:08:00 Author:lynne | Keyword: Battery Charger

Battery Charger Circuit, 12V
This battery charger circuit can be used to charge one or more batteries with the total nominal voltage of 12 V, meaning ten NiCd battery or six 2 V lead acid. The circuit is pretty small and can be built in a housing network adapter. The incorect usage is impossible: connecting the batteries with reverse polarity, shortcircuit of the output terminals or power loss have no impact on the charger or battery. google_ad_client= ca-pub-9265205501290597 ;google_ad_slot= 6648404198 ;google_ad_width=336;google_ad_height=280; We can use a transformer with 18 V on the secondary and then using a diode bridge to rectify the 18V ac voltage we get 22V dc on C1. The completely discharged batteries are charged at the begining with a 6 mA current thru R2-D2 and R4-R6-D1. One the bat. have reached 0.3 – 0.5 V, the base-emitter voltage of T1 is high enough to bring the transistor in conduction. Green LED D4 is used as an charging indicator and opens T1.There is a 60 mA current flowing thru R5-R6, this means that the charging of a 500 mAh NiCd battery will take 12 hours. If the battery is connected with reversed polarity or there is a shortcircuit, the power transistor T1 remains blocked and the charging current can not exceed 6 – 12 mA. The current draw at maximum load is around 80 mA. Battery charger circuit schematic Components List R1 = R2 = 10KR3 = 1KR4 = 5.6KR5 = R6 = 12Ω C1 = 1nFC2 = 220µF / 35V D1 = 1N4001D2 = D3 = 1N4148D4 = green LED T1 = BD140T2 = BC546   (View)

View full Circuit Diagram | Comments | Reading(733)

Cell Phone Charger Using 1.5V Battery Circuit

Published:2013/11/18 20:37:00 Author:lynne | Keyword: Cell Phone Charger

Cell Phone Charger Using 1.5V Battery Circuit
For the cell phone to charge, charger output must be above 4V and can deliver a maximum current of 500mA. This charger circuit will step up the voltage from 1.5V to 5V DC to reach the cell phone charging requirement. The circuit uses only an AA or AAA 1.5v battery (1V to 2.4V). The charger is composed of simple oscillator, a rectifier, and voltage regulator. This is similar to the Joule Thief circuit. The feedback winding F is composed 5 turns of #30 AWG magnetic wire and main winding P is composed of 6 turns of #24 AWG wire. The 5.1V zener diode and 2200uF capacitor regulates the output voltage to ensure proper charging. The windings are not critical, you can experiment using different number of turns. If ever the charger doesn’t have any output, try to reverse the winding connection. Cellphone charger circuit schematic Will it charge a cell phone battery? Yes, sure it can, I'll explain why Yes, I think so I do not know, let me try it No, I'll tell you in the comment section why not Other, I will write a comment below google_ad_client= ca-pub-9265205501290597 ;google_ad_slot= 6648404198 ;google_ad_width=336;google_ad_height=280;   (View)

View full Circuit Diagram | Comments | Reading(1432)

Car Battery Charger with Transistors Circuit

Published:2013/11/11 19:20:00 Author:lynne | Keyword: Car Battery Charger

Car Battery Charger with Transistors Circuit
This car battery charger circuit can be used to charge 12V and 6V batteries. If it is used a transformer that can deliver 4A to 5A at a voltage between 12.6V and 16V then we can get rid of the switch for 6V or 12V batteries. 12V car battery charger circuit schematic The car battery charging current is automatically limited to 4.2A. If there is a 600mV voltage on R1 (4A thru it), then the T1 transistor starts to conduct. Excessive charging current is avoided because the current value on T3′s base is limited. The difference between applied load current (at T4′s collector) and real voltage of the battery is balanced thru T4′s collector-emitter junction. The power input of T4 (2N3055) is the product of load current and voltage difference already mentioned. When charging 6V car battery this power reaches a maximum of 40W. The rectifier diodes must be able to deliver 4A at 40V. T4 2N3055 must be mounted on a good heatsink in order to dissipate the heat.   (View)

View full Circuit Diagram | Comments | Reading(1097)

3V to 24V Variable Power Supply

Published:2013/10/30 21:36:00 Author:lynne | Keyword: Power Supply

3V to 24V Variable Power Supply
This 3V to 24 volt variable-regulated power supply can be adjusted from 3 to 25 volts and is current limited to 2 amps as shown, but may be increased to 3 amps or more by selecting a smaller current sense resistor (0.3 ohm). The 2N3055 and 2N3053 transistors should be mounted on suitable heat sinks and the current sense resistor should be rated at 3 watts or more. Voltage regulation is controlled by 1/2 of a 1558 or 1458 op-amp. The 1458 may be substituted in the circuit below, but it is recommended the supply voltage to pin 8 be limited to 30 VDC, which can be accomplished by adding a 6.2 volt zener or 5.1 K resistor in series with pin 8. The maximum DC supply voltage for the 1458 and 1558 is 36 and 44 respectively. The power transformer should be capable of the desired current while maintaining an input voltage at least 4 volts higher than the desired output, but not exceeding the maximum supply voltage of the op-amp under minimal load conditions. The power transformer shown is a center tapped 25.2 volt AC / 2 amp unit that will provide regulated outputs of 24 volts at 0.7 amps, 15 volts at 2 amps, or 6 volts at 3 amps. The 3 amp output is obtained using the center tap of the transformer with the switch in the 18 volt position. All components should be available at Radio Shack with the exception of the 1558 op-amp. Variable Power Supply Circuit Diagram   (View)

View full Circuit Diagram | Comments | Reading(909)

Power Supply Monitor for TTL

Published:2013/10/29 21:03:00 Author:lynne | Keyword: Power Supply Monitor

Power Supply Monitor for TTL
Power Supply Monitor for TTL

This simple TTL power supply monitor circuit monitors the 5-volt level TTL power line and gives a signal whether the supply voltage is outside or within the necessary range or “window”. The heart of thepower supply monitoris a low-current integrated window comparator. The center of this window is set at 2.5 volt +/- 0.005 volt by the bandgap reference diode D1 which is connected to pin 2 of LTC1042. The width of this window must be 20% (+/- 10%) of the reference voltage.The reference voltage is reduced by 25% through R4 and R5 and fed to pin 5 of the IC. The monitored voltage is then fed to pin 2 so that the green LED D2 will light up when the voltage is within the desired range. Otherwise, the red LED D3 will light up signalling that the voltage is out of range. TTL power supply monitor circuit diagram   (View)

View full Circuit Diagram | Comments | Reading(526)

LM2678 Voltage Regulator Circuit

Published:2013/10/29 20:49:00 Author:lynne | Keyword: Voltage Regulator Circuit

LM2678 Voltage Regulator Circuit
LM2678 Voltage Regulator Circuit
LM2678 Voltage Regulator Circuit

The LM2678 series of regulators are monolithic integrated circuits for a step-down switching voltage regulator capable of driving up to 5A loads with excellent line and load regulation characteristics. High efficiency (>90%) is obtained through the use of a low ON-resistance DMOS power switch. The series consists of fixed output voltages of 3.3V, 5V and 12V and an adjustable output version. LM2678 12vdc 5amp voltage regulator schematic LM2678 features Efficiency up to 92% Simple and easy to design with (using off-the-shelf external components) 120 mΩ DMOS output switch 3.3V, 5V and 12V fixed output and adjustable (1.2V to 37V ) versions 50μA standby current when switched OFF ±2%maximum output tolerance over full line and load conditions Wide input voltage range: 8V to 40V 260 KHz fixed frequency internal oscillator LM2678 applications Simple to design, high efficiency (>90%) step-down switching voltage regulators Efficient system pre-regulator for linear voltage regulators Battery chargers   (View)

View full Circuit Diagram | Comments | Reading(584)

Simple 12V DC Power Supply Circuits

Published:2013/10/28 20:23:00 Author:lynne | Keyword: Power Supply Circuit

Simple 12V DC Power Supply Circuits
Simple 12V DC Power Supply Circuits
Simple 12V DC Power Supply Circuits
Simple 12V DC Power Supply Circuits

Here are 4 simple 12V power supply circuits with output voltages around 12V. First power supply circuit is built with BD139, one zener diode and a few passive components. Each of the schematic is very simple to construct and will function without problems if you respect the maximum power supply ratings. 12V dc power supply schematics 12V BD139 power supply circuit LM7812 power supply schematic A very simple PS circuit with the basic 3 Amper version of LM7812 IC. LM317 variable power supply circuit 2N3055 adjustable power supply schematic This power supply circuit has a over-current protection and a good stabilized voltage. It can deliver up to 1.6 A.   (View)

View full Circuit Diagram | Comments | Reading(1169)

220V Power Line Interface

Published:2013/10/28 20:18:00 Author:lynne | Keyword: Power Line Interface

220V Power Line Interface
This simple 220V power interface is intended as an interface for monitoring electric equipments and devices using a computer. The interface only senses whether the device being monitored is turned on or off. The most important aspect of the circuit is the galvanic isolation between the AC main line being monitored and the interface to the computer. This is done with the use of the optocoupler IC TIL111 but a suitable replacement can be used too. Main power live interface circuit diagram To avoid having to modify the circuit for each device being monitored, the circuit monitors the device’s AC power line directly. The resistor R1 lets a current of around 0.5 mA through the optocoupler LED. The other half of the current is rectified through the diode D1. It is obvious that the current to the optocoupler LED is half wave rectified. This means that the phototransistor part of the optocoupler receives only light impulses of around 100uA. The capacitor C1 filters out the current pulsation and maintains a smooth output current. In case the current pulsation is needed, just remove C1.   (View)

View full Circuit Diagram | Comments | Reading(780)

3A Adjustable Power Supply

Published:2013/10/24 20:14:00 Author:lynne | Keyword: Adjustable Power Supply

3A Adjustable Power Supply
This is a compact adjustable power supply that delivers a stable voltage and currents up to 3 amperes. The circuit is very conventional and its voltage output can be varied from 1.25 volts to 25 volts.The main module is the LM350 IC which integrates a voltage regulator and a power stage. It also has a built-in overload protection which activates at 30 watts of power dissipation. The voltage output is set by connecting the “adj” pin of the IC to the voltage divider made of R1 and P1. The output voltage can be calculated using the following formula: 1.25V x (1 + P1/R1) where the P1 value is between 0 and 2.5 KΩ. Capacitor C1 is a common ripple filter while capacitors C2 and C3 improves the regulation. The diodes D1 and D2 serves as protection for the regulator IC when the IC output is turned off. Resistor R1 is 120Ω. This ensures that the minimal load current for the IC (around 3.4mA) is high enough to maintain good performance. 3 Ampere power supply circuit schematic One thing that is most important in building the electronic circuit: provide adequate heatsink for the LM350 IC. The power dissipation at the IC is very high, around 85 watts.Consider that the heat resistance of a TO-3 package is 1.5oC/W and the maximum allowable temperature is 150oC. If a heatsink is used with a heat resistance of 1.5oC/W, when the total heat resistance is 4oC/W. At 30 watts dissipation and 25oC outside temperature, the resulting internal IC temperature is 145oC. Once this dissipation level is reached, the internal protection activates shutting down the IC. One way to avoid high dissipation levels is to use a lower voltage transformers when needed output voltages are low. To put it simply: if you are using the circuit to supply voltages around 9 volts, do not use a 25 volts transformer but use a lower voltage one instead (e.g. 12 or 15 volts).   (View)

View full Circuit Diagram | Comments | Reading(690)

General Purpose Power Supply

Published:2013/10/23 20:30:00 Author:lynne | Keyword: General Purpose Power Supply

General Purpose Power Supply
This general purpose power supply can e used for supply output voltages from 1 to 35V. The line transformer should be selected to give about 1.4 times the desired output voltage from the positive side of filter capacitor C1 to ground. Potentiometer R2 sets the output voltage to the desired value by adjusting the reference input.Rsc is the current limit set resistor. Its value is calculated as: Rsc = 0.65V/IL For example, if the maximum current output is to be 1A, Rsc = 0.65/1 = 0.65ΩThe 1kΩ resistor, Rs, is a light-loaded resistor designed to improve the no-load stability of the supply. General power supply circuit schematic   (View)

View full Circuit Diagram | Comments | Reading(0)

Universal Power Supply Circuit

Published:2013/10/23 20:29:00 Author:lynne | Keyword: Universal Power Supply Circuit

Universal Power Supply Circuit
This universal power supply contains, beside the bridge rectifier, a voltage stabilizer (78xx) and a pnp power transistor. This combination allow a load current up to 5 A. As you know a voltage stabilizer in a TO-220 package can deliver up to 1A. The additional power transistor takes the load current of about 200mA.The transformer voltage must be greater with 4V than DC stabilized voltage. C1 is calculated for 1A/1000uF, so at 5A C1 must have 4700uF. Both, transistor and voltage stabilizer must be mounted on a heatsink. Universal power supply circuit diagram   (View)

View full Circuit Diagram | Comments | Reading(842)

OverVoltage Protection Circuit

Published:2013/10/22 21:52:00 Author:lynne | Keyword: OverVoltage Protection Circuit

OverVoltage Protection Circuit
This overvoltage protection or crowbar protection circuit is used where we need protection against high voltage surge. The circuit has a few components, it is very easy to build and will protect your electric equipment againg overvoltages. The crowbar circuit must be mounted between power supply and the protected device. The over voltage protection circuit is based on brute force: when the power supply voltage increases too much a thyristor shortcircuit the output. This mean that the overvoltage is quickly removed from equipment power terminals and F1 fuse will burn. The voltage at which the crowbar protection starts is set between 5V and 25V with P1: adjust P1 at maximum resistance value. temporarily replace the fuse with a wire and connect the crowbar circuit at a variable power supply. adjust the current limitation at 1 A si the output voltage at the desired value to activate crowbar protection. slowly rotate P1 until activation of the thyristor (when the current limitator engages) The overvoltage (crowbar) circuit is now set. Replace the wire bridge with a fuse (5A). In repaos state the circuit take 1 mA. Over Voltage/Crowbar Protection Circuit Diagram   (View)

View full Circuit Diagram | Comments | Reading(1667)

Reverse Polarity Protection Battery Charger

Published:2013/10/22 21:50:00 Author:lynne | Keyword: Reverse Polarity Protection Battery Charger

Reverse Polarity Protection Battery Charger
This reverse polarity protection NiCd battery charger can charge up to 7 NiCd batteries connected in series. This number can be increased if the power supply is increased with 1.65V for each supplementary battery. If T2 is mounted on a proper heatsink, the input voltage can be increased at a maximum of 25V. Unlike most of comercial NiCd chargers available on the market, this charger has a reverse polarity protection. Another great quality is that it does not discharge the battery if the charger is disconnected from the power supply. Usually , NiCd batteries must be charged in 14 hours at a charging current equal with a tenth percent from battery capacity. For example, a 500 mAh is charged at 50 mA for 14 hours. If the charging current is too high this will damage the battery. The level of charging current is controlled with P1 between 0 mA – 1000 mA. T1 is opened when the NiCd battery is connected with the right polarity or if the output terminals are empty. T2 must be mounted on a heatsink. If you cannot obtain a BD679, then replace it with any NPN medium power Darlington having the output parameters at 30V and 2A. By lowering R3 value the maximum output current can be increased up to 1A. NiCd Battery Charger Circuit Diagram   (View)

View full Circuit Diagram | Comments | Reading(714)

Desktop PC Linear Power Supply Circuit

Published:2013/10/22 21:48:00 Author:lynne | Keyword: Desktop PC Linear Power Supply Circuit

Desktop PC Linear Power Supply Circuit
Useful for electronics hobbyists, this linear workbench desktop power supply circuit converts a high input voltage (12V) from the SMPS of a PC into low output voltage (1.25 to 9 volts). An adjustable three-pin voltage regulator chip LM317T (IC1) is used here to provide the required voltages. The LM317T regulator, in TO-220 pack, can handle current of up to 1 amp in practice. Desktop PC power supply circuit diagram The diagram shows the circuit of the desktop power supply. Regulator IC LM317T is arranged in its standard application. Diode D1 guards against polarity reversal and capacitor C1 is an additional buffer. The green LED (LED1) indicates the status of the power input. Diode D2 prevents the output voltage from rising above the input voltage when a capacitive or inductive load is connected at the output. Similarly, capacitor C3 suppresses any residual ripple. Connect a standard digital voltmeter in parallel with the output leads to accurately set the desired voltage with the help of variable resistor VR1. You can also use your digital multimeter if the digital voltmeter is not available. Switch on S1 and set the required voltage through preset VR1 and read it on the digital voltmeter.Now the power supply is ready for use. The circuit can be wired on a common PCB. After fabrication, enclose the circuit in a metallic cover. Then open the cabinet of your PC and connect the input line of the gadget to a free (hanging) four-pin drive power connector of the SMPS carefully.   (View)

View full Circuit Diagram | Comments | Reading(522)

Variable Power Supply with 78XX regulator

Published:2013/10/21 20:41:00 Author:lynne | Keyword: Variable Power Supply

Variable Power Supply with 78XX regulator
This variable power supply is using 7805, 7809, 7812 or 7815 voltage regulators, where the last 2 digits represents the maximum output voltage of the IC.This circuit offers excellent ripple rejection, eliminates mains hum, and has a design using a pi filtered C-L-C. A core should be chosen to work within the specific frequency as stated by the manufacturer. L1 is a powder core and has 32 turns of 0.75mm wire. Variable Power Supply Circuit Diagram The transformer has a 240V primary and has a secondary rated 24V at 2A. The bridge rectifier contains 4 diodes, their current rating needs to be high with respect to the transformers output current; if not the current may damage the diodes. C1 is the mainfiltering capacitor, the supply is further smoothed by the combination of L1 and C3. C2 and C4 are decoupling capacitors; their action further reduce ripple factor. The regulator 78xxr, U1 utilizes the action of zener diode ZD1 which is in parallel with the potentiometer, R1. The tuning action of R1 produces a variable regulator output. The output voltage is variable from the regulator output to the regulator output plus the zener voltage. E.G. A 7805 regulator and 10V zener give an output adjustable from 5 to 15 Volts. The regulator may be changed to provide different output voltages as may the zener. the zener should be rated a minimum of 1.3 Watts. T1 Transformer 10:1 Secondary 24V @ 2ABR1 Bridge Rectifier 50V PIV 2A ratingU1 7805 N.B. This may be changed for different output voltages e.g. 7812 for higher output voltageZD1 15V zener @ 1.3W   (View)

View full Circuit Diagram | Comments | Reading(1134)

Increase Regulator Voltage Output

Published:2013/10/17 20:22:00 Author:lynne | Keyword: Increase Regulator Voltage Output

Increase Regulator Voltage Output
It is often necessary to arrange an voltage regulator IC to give a higher output voltage than that set by the regulator alone. One method to achieve this is by connecting the “common” terminal to the mid-point of a potential divider but the problem with this method is that IC regulators have a small quiescent current (~10mA) flowing out of the common terminal to ground.The magnitude of this quiescent current is not closely controlled and hence the total output voltage becomes somewhat unpredictable. Low divider resistor values help, but there are likely to be complications of heat dissipation and inefficiency. The circuit presented here avoids the problem by using the transistor T1 to generate a low impedance at the regulator common terminal by emitter-follow action, while transferring the voltage divider from a relatively high-resistance divider network. The value of R3 is not critical but must be low enough to accept the highest quiescent current without causing T1 to turn-off.   (View)

View full Circuit Diagram | Comments | Reading(589)

LDO 5V Voltage Regulator with MCP1755

Published:2013/9/5 19:57:00 Author:lynne | Keyword: LDO 5V Voltage Regulator with MCP1755

LDO 5V Voltage Regulator with MCP1755
This LDO (low-dropout) voltage regulator is built with MCP1755 and can deliver 5V and currents up to 300 mA with a input voltage range between 5.5V to 16V. The LDO output is stable when using only 1 µF of output capacitance. Ceramic, tantalum or aluminum electrolytic capacitors may all be used for input and output. Overcurrent limit and overtemperature shutdown provide a robust solution for any application.   (View)

View full Circuit Diagram | Comments | Reading(571)

1KHz Sinewave Generator

Published:2013/7/30 20:44:00 Author:muriel | Keyword: 1KHz , Sinewave Generator

1KHz Sinewave Generator
Parts:R1 5K6 1/4W ResistorR2 1K8 1/4W ResistorR3,R4 15K 1/4W ResistorsR5 500R 1/2W Trimmer CermetR6 330R 1/4W ResistorR7 470R Linear PotentiometerC1,C2 10nF 63V Polyester CapacitorsC3 100µF 25V Electrolytic CapacitorC4 470nF 63V Polyester CapacitorQ1,Q2 BC238 25V 100mA NPN TransistorsLP1 12V 40mA Lamp (See Notes)J1 Phono chassis SocketSW1 SPST Slider SwitchB1 9V PP3Clip for 9V PP3 Battery Circuit description:This circuit generates a good 1KHz sinewave using the inverted Wien bridge configuration (C1-R3 & C2-R4). Features a variable output, low distortion and low output impedance in order to obtain good overload capability. A small filament lamp ensures a stable long term output amplitude waveform. Useful to test the Audio Millivoltmeter, Audio Power Meter and other audio circuits published in this site. Notes:The lamp must be a low current type (12V 40-50mA or 6V 50mA) in order to obtain good long term stability and low distortion.Distortion @ 1V RMS output is 0.15% with a 12V 40mA lamp, raising to 0.5% with a 12V 100mA one.Using a lamp differing from specifications may require a change in R6 value to 220 or 150 Ohms to ensure proper circuit's oscillation.Set R5 to read 1V RMS on an Audio Millivoltmeter connected to the output with R7 fully clockwise, or to view a sinewave of 2.828V Peak-to-Peak on the oscilloscope.With C1,C2 = 100nF the frequency generated is 100Hz and with C1,C2 = 1nF frequency is 10KHz but R5 is needing adjustment.High gain transistors preferred for better performance.   (View)

View full Circuit Diagram | Comments | Reading(675)

Precision Metronome and Pitch generator

Published:2013/7/30 20:41:00 Author:muriel | Keyword: Precision Metronome, Pitch generator

Precision Metronome and Pitch generator
Parts:R1 1M 1/4W ResistorR2 22K 1/4W ResistorR3 6K8 1/4W ResistorR4 4K7 1/4W ResistorR5 47K 1/4W ResistorR6 100K 1/4W ResistorR7 39K 1/4W ResistorR8 12K 1/4W ResistorC1 47pF 63V Ceramic CapacitorC2 2-22pF 63V Ceramic TrimmerC3 470pF 63V Ceramic CapacitorC4 10pF 63V Ceramic CapacitorC5 100nF 63V Polyester CapacitorC6 220nF 63V Polyester CapacitorC7 22µF 25V Electrolytic CapacitorD1-D15 1N4148 75V 150mA DiodesIC1 4060 14 stage ripple counter and oscillator ICIC2 4082 Dual 4 input AND gate ICIC3 4520 Dual binary up-counter ICIC4 4518 Dual BCD up-counter ICIC5 4046 Micropower Phase-locked Loop ICIC6 4040 12 stage ripple counter ICQ1 BC337 45V 800mA NPN TransistorXTAL 2.4576 MHz Miniature Quartz crystalSW1 BCD Miniature Thumbswheel Switch (units)SW2 BCD Miniature Thumbswheel Switch (tens)SW3 BCD Miniature Thumbswheel Switch (hundreds)SW4 SPST Slider Switch (On-off)SW5 SPDT Slider Switch (Metronome-Pitch)SPKR 8 Ohm, 50 mm. LoudspeakerB1 9V PP3 BatteryClip for 9V PP3 Battery Circuit operation:CMos IC1 and IC2B quad AND gate form a 2.4576 MHz crystal oscillator plus a 2400 times divider. IC3A provides further division by 16, obtaining a 64 Hz stable frequency square wave. This frequency is multiplied by operation of Phase Locked Loop IC5, double decade divider IC4 and IC3B 4 bit binary divider, by the number set by three miniature BCD thumbswheel switches SW1, SW2 and SW3: units, tens and hundreds respectively.Connecting, by means of SW5, Q1 base to pin 2 of IC6, we obtain after a 64 times division, the same frequency set by thumbswheel switches with quartz precision, and no need for a scale indicator.Volume regulation of the pitch generator is obtained trimming resistor R5. In the same manner, with SW5 set to metronome, the small speaker reproduces the frequency set by thumbswheel switches but divided by 3840, thus obtaining beats per minute ratio   (View)

View full Circuit Diagram | Comments | Reading(616)

Pages:15/291 1234567891011121314151617181920Under 20