50 watt Power Amp OTL by LM3900, 2N3055

This be power amp OTL 50Watt use IC LM3900 and 2N3055 x 3pcs transistors to pillar equipment. Follow very circuit keeps to are Class ab then have a voice good loud. When , be amp OTL you then are certain that build easy use power supply the group is one 70V sizes by must use Current low 2Amp go up. Then have a voice good another thing you will like that amplifier. This durability do not make a loudspeaker a lose easy.

LM3914          IRF3205           PT4115          2N2222A            NRF24L01

MAX202CSE TRANSMITTER/RECEIVER

   

 MAX202CSE IL00 RS-232 TRANSMITTER/RECEIVER —TOP VIEW— 1 2 C1+ V+ C1+ 1 VCC 16 3 C1_ 4 6 C2+ V_ V+ 2 15 GND 5 C2_ C1_ 3 14 T1 OUT 11 14 T1 T1 10 7 T2 T2 C2+ 4 13 R1 IN 13 12 R1 R1 C2_ 5 12 R1 OUT 8 9 R2 R2 V_ 6 11 T1 IN R1, 2 : RECEIVER 1, 2 T1, 2 : TRANSMITTER 1, 2 T2 OUT 7 10 T2 IN R2 IN 8 9 R2 OUT +5 V 0.1 µF 0.1 µF INPUT 6.3 V + + 16 1 + 2 +10 V +5V to +10V 0.1 µF VOLTAGE DOUBLER 3 + 4 _10 V +10V to _10V 0.1 µF VOLTAGE INVERTER 6 0.1 µF 5 +16 V +5 V 400 K 11 14 T1 +5 V TTL/CMOS RS-232 INPUTS OUTPUTS 400 K 10 7 T2 12 13 R1 5 K TTL/CMOS RS-232 OUTPUTS INPUTS 9 8 R2 5 K 15

MMBT3904 NPN switching transistor

The MMBT3904 is a NPN General Purpose Amplifier. This device is designed as a general purpose amplifier and switch. The useful dynamic range extends to 100 mA as a switch and to 100 MHz as an amplifier.

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Absolute maximum ratings: (1)Collector-Emitter Voltage: 40 V; (2)Collector-Base Voltage: 60 V; (3)Emitter-Base Voltage: 6.0 V; (4)Collector Current - Continuous: 200 mA; (5)Operating and Storage Junction Temperature Range: -55 to +150 ℃.

Features: (1)Collector-Emitter Breakdown Voltage: 40 V at IC = 1.0 mA, IB = 0; (2)Collector-Base Breakdown Voltage: 60 V at IC = 10 μA, IE = 0; (3)Emitter-Base Breakdown Voltage: 6.0 V at IE = 10 μA, IC = 0; (4)Collector Cutoff Current: 50 nA at VCE = 30 V, VEB = 3V.

solated Full Duplex RS232C Interface Circuit 6N137

This is a Isolated Full Duplex RS232C Interface circuit. This circuit is used to protect PC from direct connection to hazardous voltages. Feature : isolate TxD and RxD lines from the PC serial port , baud rate of 19.2k baud, 5V supply. Component : capacitor, 1N4148 diode, LED, DB9, terminal block resistor, 6N137, CNY17-3, 74HC14. 

700W Power Amplifier with 2SC5200 & 2SA1943

700W Amplifier Adjust the amplifier power 700W looks calm, but we requirement not put out of your mind to the adjustment happening forcing transistors, the whole relating to-engagement of frequency offset. It is compulsory to change the current insurance rule which serves to guard the final transistors. Their tendency to happen allowable to keep the transistors in the SOAR characteristics. primary it was needed to evaluate all the necessary resistors and subsequently measured to verify the accuracy of the calculations, it is managed with satisfactory results. Peripheral changes required in support of it to be there able to consistently amplifier to supply power. - First you need to restore the 2k2 resistors stylish string with the LEDs on Zenerovými resistors with upper wattage. be enough 1/2W resistors, power loss next to 80V +-based 1W. - therefore was traded 1k2 resistor in the pointer resistor by the side of 620 ohms.


Which is the initial reap has doubled, so at this point is the overall gain amplifier 40 and the limit excitation is sufficient to 1V rms. - Předbudiči transistors were replaced by stronger MJE15032/33 since KF467/470 are permitted satellite dish current 20mA - by the side of the exciter output stages are used the same transistors for example the output stage. - add up to of terminals of transistors has been increased to eight pairs - It had to occur to compensate designed for the excitation level by calculation a capacitor 10pF to 47pF + 22K appendage. This led to a slight "gradual" amplifiers, but this did not affect the ensuing parameters. This power is tuned correctly in support of this type of terminal transistors 2SA1943/2SC5200.

With with the purpose of it is a least assessment next to which the amplifier operates stably exclusive of pass by the side of the rising and falling edges of the genuine. - The ultimate adjustment, the adjustment terminal current protection transistor. The SOAR transistor characteristics shows with the intention of the most allowable radio dish current once the voltage of 1.5 A is ideal in favor of cooling, so it's essentially not as much of. Therefore, the current protection is customary to 12A, single-arm. This impersonate protection SOAR transistor characteristics. curt-circuit current is regarding 6 A which is about 075A for every transistor. This is far beneath the SOAR characteristics. The mechanical design is relatively clear-cut, the transistors are placed on the two cooling profiles with a height of 66 mm, width 44mm, overall part 260mm. They are twisted contrary to each one other in this way, from the cooling tunnel. Coolers are attaching the nylon aid which allows the compilation of transistors exclusive of washers, and thus better conveying tepla.DPS amplifier next to the top of the tunnel and the transistors are soldered from the underside of PCB.

Driving Circuits from a CR2032 Lithium Coin Cell

Recently I have tested an complete over the top design which pushed the poor little CR2032 far beyond its limits. Time to grab a few facts from the datasheet for further reference.

To get a good example I found a quite elaborate CR2032 datasheet from Duracell. I think other batteries behave quite similar to this.

The general key fact of an CR2032 are obvious and quite easy to grab from the datasheet:

Voltage: 3V

Capacity: 240mAh (to 2.0V)

If you study the datasheet more closely you will see that the voltages drop sharply after it reaches 2.8V (after it has delivered about 170mAh).

ESR (Equivalent Series Resistor):about 18 to 20 Ohms.

The ESR (Equivalent Series Resistor) or IR (Internal Resistance) is quite flat up to 150mAh of capacitance – there it reaches about 20 Ohms. At 170mAh it reaches something like 30 Ohms. This is quite hefty. In comparison good capacitors have a series resistance from some Ohms to a fraction of an Ohm – so it is always good to put some (even electrolytic) capacitors in parallel to the battery. If you are concerned that switching on or of of your circuits discharges the battery to much by charging up the capacitors – there is a simple trick to prevent it: put the capacitors in front of the ‘on’ switch so that are always charged and will not charge after your circuit is switched on. The leakage current will be so small that it will be neglectable in most cases.

But if you want to calculate how much constant current you can draw from these batteries you have to use Ohm’s law:

V = R * I or I = V /R

If you take the later and say you want no voltage drop higher that 1.2 Volts – because after that your circuit reaches 1.8 Volts which makes your microcontroller most probably going brown out. Applying these with the ESR of 20 Ohms, you will get something like 60 mA you can draw by them (I = 1.2V/20Ohm). You if calculate more conservative and do not want to go below 2.8V – which gives you some 0.2 Volts head room  – you will only be able to draw 10 mA (I = 0.2V/20Ohm) – just enough for an LED. These calculations do not consider the voltage drop of the battery of its life time.

In the bottom line: If you use those batteries you have to consider the 20-30 Ohms series resistance. Especially if you draw some constant current (spikes can be easily removed using capacitors). Yo have to assume 170mAh as maximum capacitance because then the CR2032 reaches 2.8Volts and the ESR goes up to a whopping 30 Ohms – going up from there very steep. Because of the high ESR of the CR2032 you will most probably not be able to draw more than 20-30 mAh safely (as constant current).

Perhaps it is even better to get a boost converter to 3 or 3.3V – to suck out all the juice in the battery. This should should be good for the environment too. Or even better get rechargeable Lithium Cells.

So driving an RGB with an 5V boost op converter is impossible. At white (all three LEDs draw 20mA) it is 60mA current at 5V, considering a efficiency of 80% this will give you more than 120 mAh at 3.3V. Impossible or the CR2032. So my intended design will never work. I wish I had done those calculations before I designed it and not after I saw that the prototype does not work.


As we see the higher the current is the more loss we get by the ESR of 20 Ohms. So the question is how much power we can get from an CR2032. If we want to draw the maximum amount of power over a short time we simply take the power:

P=V*I

And we know that the voltage is

v=3-20*I

And we get

P=(3-20*I)*I

If we create a little graph from it we get

So we see that the maximum is somewhere at 75mA and somwhere at 0,1125 Watts. Perhaps the real theoretical value is a bit off – but most real batteries will be a bit off too, so it is a good enough aproximation.

So that is somewhat consistent to our previous calculations to not exceed 80mA to avoid a too big voltage drop.

But how many energy can we draw from an CR2032? For this we simply calculate the watt hour of the battery:

e=P*t and t=0,24A/I

so we get

e=(0,24/I)*P

or

But this is not very astonishing. The less current you draw the less loss you got at the internal resistor. But I am unsure if there is this resistor, which burns energy to heat. But since the batteries get hot if you draw too much power you will get some loss. But I do not think that the loss is equal to a 20 Ohm resistor. But the main finding is clear – the more current you draw the more loss you have.

From the comments I got the tip to put the lithium coin cells in series to get a higher coltage at the current draw. But this will enlarge the voltage swing at different current levels (from 6V at 0mA to 3V at 150mA). This can be dangerous for your circuit. A better approach would be to put the batteries in parallel to half the internal ESR – so you would still get 1.5 Volts at 150mA.

Of course to counter current spikes you should allways put sufficiently sized capacitors in parallel. Sufficiently sized depends on the level of current spikes and there time. Just check out how a Farad is defined and you can derrive the needed value (which is the product of voltage change and time).

But in most of my designs space is a rare good. So no parallel batteries and no big capacitor banks.

Something that could work is sucking the power with a boost converter to get a steady output voltage independent of the current draw. This would of course enhance the loss but at least we get the voltage we want at an expense of the efficiency.

Driving stepper motor using ULN2003

The simplest way to drive stepper motor having lower current rating is using ULN2003. The ULN2003 contains seven darlington transistors. The ULN2003 can pass upto 500mA per channel and has an internal voltage drop of about 1V when on. It also contains internal clamp diodes to dissipate voltage spikes when driving inductive loads. The circuit for driving stepper motor using ULN2003 is shown below.

For higher current torque motors, you can use TIP120. The advantage is that the TIP120 can pass more current along with heat sink. The disadvantages are that the more wiring is required and four TIP120 is used to control the motor.

Fairchild Semiconductor 1N4001

1 AMP GENERAL PURPOSE SILICON DIODES.

 

2 projects have used Fairchild Semiconductor 1N4001

 

• The plastic package carries Underwriters Laboratory Flammability Classification 94V-0
• Construction utilizes void-free molded plastic technique
• Low reverse leakage
• High forward surge current capability
• High temperature soldering guaranteed: 250 C/10 seconds,0.375 ” (9.5mm) lead length, 5 lbs. (2.3kg) tension

 

 

NE555 Basic Monostable

Here the popular NE555 timing IC, is wired as a monostable. The timing period is precise and equivalent to:

1.1 x R1 x C1

With component values shown this works out at approximately 1.1msec.The output duration is independant of the input trigger pulse, and the output from the 555 is buffered and can directly interface to CMOS or TTL IC's, providing that the supply voltages match that of the logic family.

The timing diagram above shows the output pulse duration, the trigger input and the output at the discharge terminal of the IC.

Microcontroller interface using RS485 & RS422

After a period of research, I found out that RS485 and RS422 is in fact the same.

RS422 is a duplex configuration. RS422 using 4 wire to communicate in both direction. One pair of wire to do transmit and the other pair to receive. Both sides is able to transmit and receive at the same time.

RS485 is a half duplex configuration. RS485 using only 2 wire to communicate in both direction. With only two wire, it means that when one side is transmitting, the other side of the communication line will be receiving. Both side cannot be transmitting at the same time. For RS485 transceiver, use MAX485 or MAX3485. They have the same pin out except that MAX485 uses 5V supply, MAX3485 uses 3.3V supply.

RS422 can be connected to work with RS485 to either receive or transmit date, but not both. RS422 can be wired directly using a pair of wire, +ve to +ve, -ve to -ve terminal. For RS422 transceiver, use MAX488 or MAX3488. They have the same pin out except that MAX488 uses 5V supply, MAX3488 uses 3.3V supply.

FR107 1.0AMP. Fast Recovery Rectifiers

This is one package pinout of FR107 .

FR107 1.0AMP. Fast Recovery Rectifiers.

 

• ● Fast switching for high efficiency
• ● Low cost
• ● Diffused junction
• ● Low reverse leakage current
• ● Low forward voltage drop
• ● High current capability
• ● The plastic material carries UL recognition 94V-0

 

• ●Case: JEDEC DO-41 molded plastic
• ●Polarity: Color band denotes cathode
• ●Weight: 0.012 ounces , 0.34 grams
• ●Mounting position: Any

Aquaponics pH to 1-Wire Converter – Part 2 BAT54S

This is the first draft of the pH to 1-Wire converter schematic, and some of the component values are still missing. The original circuit runs on 12 VDC, but since the A/D converter IC must be supplied with 5 VDC only I want to scale down the circuit, so that 5 V is the maximum voltage present. I assume I would have to tweak some resistor values in order to make the circuit run at this lower supply voltage, but I haven’t looked into the details yet. I’ll post an updated schematic and the calculations later.

BAT54S

The original idea was to use a 1-Wire A/D converter with built-in 1-Wire digital interface, but the one I found was not recommended for new designs. This is what Maxim writes about the DS2450 A/D converter:

    This product is Not Recommended for New Designs. Some versions may be No Longer Available or being discontinued and subject to Last Time Buy, after which new orders can not be placed.

Also known as ‘NRND’. Most of the other A/D converters I found at Maxim had another interface, but the main IC on the soil moisture sensor board from Hobby Boards also converts analog signals to digital and that’s a DS2760. The updated version is called DS2762, which is the one that I have used in the new circuit.

The DS2760 on the soil moisture sensor board measures current, but the IC also has a voltage input pin. The IC is actually a ‘High-Precision Li+ Battery Monitor With Alerts’ as Maxim calls it. The idea is to only use the voltage input pin and 1-Wire interface to get a popular, and cheap, A/D converter, with high input resistance.

Since the DS2762 operates on 5 VDC, the ground reference for the amplifier section should be changed to 2.5 V instead of 7 V in order to use the entire input voltage span of the A/D converter. The 7 V in the original circuit was meant to be measured with a voltage meter and you would have the pH value directly as a reading (pH 7 = 7.00 V, pH 8 = 8.00 V etc.). There’s no meter or display on this new circuit, only data delivered to a computer via the 1-Wire interface, so voltages in the circuit can be converted to something meaningful using software on the computer. Historical data can be displayed with e.g. RRDtool.

When the supply voltage is changed, the gain of the voltage amplifier has to change too, along with a change in offset voltage, i.e. ground reference. IC300 is a dual op-amp IC, where R351, R352 and R355 determines the gain. R300 sets the ground reference voltage level. Apparently it is necessary to put in trimmer resistors, since practical op-amps are not perfect like theoretical ones. Also, the pH probe is worn down as time goes by, and the circuit will have to be calibrated regularly.

Several capacitors have been added to short circuit any fast changing signals as these are irrelevant to aquaponics pH measurements and any alternating currents are considered noise in this respect. It means that the pH values from the 1-Wire interface will need seconds to stabilize. D101 is included to protect the 1-Wire interface.

Since the schematic does not represent the PCB layout, a note has been written about the seemingly long wires going from the BNC connector to the op-amp. On the actual PCB the traces must be as short as possible, because the internal resistance of a pH probe is very high and any electromagnetic radiation will induce relatively high unwanted voltages in the circuit. It shouldn’t be a problem though to place IC300 close to J300.

DS2762 has a general purpose I/O pin (PIO) which can be used for debugging. D100 could be connected to this pin to be able to signal something, but it would probably need an extra transistor. As I want things to be as simple as possible I haven’t included this, but at least there’s a resistor footprint to work with now.

I want to experiment with the values of R351, R353, R354 and R355 in Qucs, as I don’t fully understand the impact of changing the supply voltage, hence the missing resistor values. But I don’t mind – Qucs turns out to be an awesome piece of software for the electronics hacker ;-)

   

IRFP250N Power MOSFET

Fifth Generation HEXFETs from International Rectifier utilize advanced processing techniques to achieve extremely low on-resistance per silicon area. This benefit, combined with the fast switching speed and ruggedized device design that HEXFET Power MOSFETs are well known for, provides the designer with an extremely efficient and reliable device for use in a wide variety of applications.

The IRFP250N TO-247 package is preferred for commercial-industrial applications where higher power levels preclude the use of TO-220 devices. The TO-247 is similar but superior to the earlier TO-218 package because of its isolated mounting hole.

IRFP250N Features

• Advanced Process Technology

• Dynamic dv/dt Rating

•175°C Operating Temperature

•Fast Switching

• Fully Avalanche Rated

•Ease of Paralleling

•Simple Drive Requirements

The inverter failure-tolerant control of single-phase sine wave is studied BTA16-600B

The failure-tolerant control purpose lies in directing against different trouble sources and symptoms, take the corresponding fault-tolerant processing measure, compensate for trouble, dispel or repair automatically, in order to guarantee the apparatus continues safe reliability service, or regard sacrificing characteristic losses as the cost, guarantee the apparatus finishes its basic function within stipulated time. If you want to adopt failure-tolerant control, have structure or redundancy functionally in the real-time analysis system at first. Find through analyzing, as to the inverter circuit of single-phase full-bridge, in fact the structural redundancy exists. Can regard the whole-bridge circuit as the superposing of two pieces of half bridge converter, if can be after the gas switching tube trouble of the power of a bridge arm of the inverter of the full-bridge, blockade this bridge arm, reconstruct the characteristic of certain holding circuit as the half bridge converter of the whole-bridge circuit, realize failure-tolerant control. Fig. 1 is the equivalent electrical circuit that the circuit reconstructs after full-bridge circuit topology with fault-tolerant capability and first, two bridge arm switch troubles.

In Fig. 1a, divides into two the electric capacity C1 as half bridge converter of the direct-flow Filtering capacitance in the whole-bridge circuit, C2, links the first bridge arm middle point A with two electric capacity middle points o with the bidirectional thyristor VTr1, the bidirectional thyristor VTr2 links the second bridge arm middle point B with point o, forms full-bridge circuit topology with fault-tolerant capability in this way.
Normal working hour, VTr1, VTr2 is the off state, the circuit equivalent is the normal full-bridge inverter circuit. After the trigger impulse takes place and lose the trouble in the power tube VM1, adopt the fault-tolerant control strategy to close the power tube VM3 of the same bridge arm, touch off VTr2 to turn on at the same time, VTr1 keeps off, the whole-bridge circuit is reconstructed as the half bridge converter, the circuit equivalent, in order to pursue 1b at this moment. After the trigger impulse takes place and lose the trouble in the power tube VM2, adopt the fault-tolerant control strategy to close the power tube VM4 of the same bridge arm, touch off VTr1 to turn on at the same time, VTr2 keeps off, the whole-bridge circuit is reconstructed as the half bridge converter, the circuit equivalent, in order to pursue 1c at this moment. The original control device should carry on corresponding adjustment according to the change of the control objective after the circuit is reconstructed, in order to guarantee the characteristic maintains at the acceptable range.
Sum up the fault-tolerant control strategy as follows, suppose VMi i =1,2,3,4The trigger impulse is lost. The whole fault-tolerant control process can be divided into the following several step: Judge the switch position of the trouble in fault detection and diagnostic circuitry; Blockade the trigger impulse of power switch on VMi and the same bridge arm in control unit, touch off the bidirectional thyristor which connects this bridge arm; The control unit changes the controller parameter, it is topological after make it adapt to reconstructing.
On the foundation of analyzing in the principle and artificial experiment, have designed and made a low-powered experimental provision. The experimental parameter is: Switching frequency fs =10 kHz; Export the filtering inductance L =1 mH; Filtering capacitance C of the output =20 F; Input the Filtering capacitance C1 =C2 =1 000 F; Direct-flow input voltage Uin =48 V. All power switches adopt the power MOSFET of the Model IRF650A, the output voltage adopts the voltage to isolate the man of great talent AD202 to measure after partial pressure. The output current measures and adopts the electric current transducer of Hall of Model CSB6-50A. The sense resistor of electric current of elementary straight flow side adopts 4 times 0. The resistance of 3 / 2 W is connected in parallel. Input the filtering resistance and is formed by two pieces of 1 000 F electric capacity, o some connect A, B bipunctate with VTr2 by VTr1. The bidirectional thyristor chooses BTA16-600B, drive and choose the bidirectional thyristor to drive special purpose chip MOC3 021. The main control chip of the circuit adopts the Model TMS302LF2407A DSP, is finished implementation of failure diagnosis and fault-tolerant tactics by it.
Experimental analogy VM1 is on the appointed phase place 90 degrees, 170 degrees, 270 degrees The trigger impulse takes place to lose the trouble, after the testing signal is judged by DSP trouble diagnostic element, carry out the fault-tolerant control procedure, blockades VM2 trigger impulse, touches off VTr1, it is 2 fold to change the given sine wave uref.

motor controller for R/C models LL4148

The complete circuit diagram of the motor control is shown in Figure 1. The schematic includes all components for unidirectional as well as bidirectional use. The desired version is chosen before building the circuit. Your choice therefore determines the components used. The circuit has been kept as compact as possible. The result: a motor control weighing less than 25grammes.

Resistors:
R1 = 4kOhm, SMD
R2 = 100Ohm, SMD
R3 = 470Ohm, SMD
R4,R6 = 100kOhm, SMD
R5 = 10Ohm SMD
R7 = NTC, 100kOhm
R8 = 1kOhm, SMD
R9 = 10kOhm, SMD

Capacitors:
C1,C2 = 15pF, SMD
C3,C5 = 100nF, SMD
C4 = 10nF, SMD
C6 = 47µF 10V SMD

Semiconductors:
D1 = LL4148*
D2 = MBR2045CT*
T1 = BC517
T2,T3,T4 = BUZ11
T5 = IRF9530
IC1 = PIC16C84 (order code 966510-1)
IC2 = L4940V5
IC3 = PC827

Miscellaneous:
K1 = 10-way pinheader
X1 = 4MHz quartz crystal
Printed circuit board and programmed PIC (IC1): set order code 960095-C
PIC also available separately: order code 966510-1

3.2 The 8255 a PI/O - Chip 82C55A

The 82C55A is a high performance CMOS version of the industry standard 8255A . It is a general purpose programmable I/O device which may be used with many different microprocessors. There are 24 I/O pins which may be individually programmed in 2 groups of 12 and used in 3 major modes of operation. The high performance and industry standard configuration of the 82C55A make it compatible with the 80C86, 80C88 and other microprocessors. Static CMOS circuit design ensures low operating power. TTL compatibility over the full military temperature range and bus hold circuitry eliminate the need for pull-up resistors.

 The device comprises three 8 bit ports whereby port c can be sub-divided into two 4 bit groups. Each of these three ports is addressed by A0 and A1 . With it's read, write, the chip select and data signals it looks and behaves like a tiny ROM or a RAM with only three bytes.

    To switch between 'RAM-' and 'ROM-mode' the 8255 has a mode register where three working modes can be selected. The mode register is selected when A0 and A1 are set to high (+5V).

    The three modes are:

    Mode 0: basic input / output
    Mode 1: strobed input / output
    Mode 2: bi-directional bus

For our purpose only mode 0 was interesting, but the device may be switched into each with the setup supplied in this document.
To work with the three ports they must first be initialized. This is done by writing the proper control word into the control register. Figure 11a shows the definition of the control word. While bit D2, D5, D6 and D7 define mode 0..2 the bits D0, D1, D3 and D4 define the settings of the ports to input- or output-mode. In other words you need to 'program' or switch the 82C55 every time you want to change a port data flow direction.
If 'all input mode' in mode 0 is requested the control word would be 10011011bin = 9Bhex = 155dec. If 'all output mode' in mode 0 shall be selected the control word would be 10000000bin = 80hex = 128dec.

3A/800V 50KHz Power Switch KA5L0380R

The Fairchild Power Switch (FPS) KA5L0380R product family is specially designed for an off-line SMPS with minimal external components. The Fairchild Power Switch (FPS) consist of high voltage power SenseFET and current mode PWM IC. Included PWM Controller integrates the fixed frequency Oscillator the under voltage lock-out, the leading edge blanking, the optimized Gate turn-on/turn-off driver, the thermal shutdown protection, the over voltage protection, and the temperature compensated precision current sources for the loop compensation and the fault protection circuitry. Compared to Discrete MOSFET and PWM Controller or RCC solution, a Fairchild Power Switch (FPS) CAN reduce total component count, design size, weight and at the same time increase efficiency, productivity, and system reliability. It has a basic platform well suited for cost-effective design in either a flyback converter or a forward converter.

DC Voltage Doubler - 74HC132

74HC132
This is a cheap DC Voltage Doubler Circuit diagram, which requires a few components and will deliver 10V from a 5V power supply. If the oscillator must be built from a non-functional gate then is required 2 more components: R1 and C3.
The most important parameters of this voltage doubler circuit are given in the table below. Note that because of the IC tolerances these data may have some differences.

TL494CN SMPS Controller

The TL494CN is a pulse-width-modulation control circuit. It incorporates all the functions required in the construction of a pulse-width-modulation (PWM) control circuit on a single chip. Designed primarily for power-supply control, the TL494CN offers the flexibility to tailor the power-supply control circuitry to a specific application. The TL494CN contains two error amplifiers, an on-chip adjustable oscillator, a dead-time control (DTC) comparator, a pulse-steering control flip-flop, a 5-V, 5%-precision regulator, and output-control circuits. It provides for push-pull or single-ended output operation, which can be selected through the output-control function.

TL494CN absolute maximum ratings: (1)VCC Supply voltage: 41 V MAX; (2)VI Amplifier input voltage: VCC + 0.3 V max; (3)VO Collector output voltage: 41 V max; (4)IO Collector output current: 250 mA max; (5)θJA Package thermal impedance:D package: 73℃/W max; DB package℃/W max: 82; N package 67 ℃/W max; NS package: 64℃/W max; PW package: 108℃/W max; (6)Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds: 260 ℃ max; (7)Tstg, Storage temperature range: –65 to 150 ℃.

TL494CN features: (1)Complete PWM Power-Control Circuitry; (2)Uncommitted Outputs for 200-mA Sink or Source Current; (3)Output Control Selects Single-Ended or Push-Pull Operation; (4)Internal Circuitry Prohibits Double Pulse at Either Output; (5)Variable Dead Time Provides Control Over Total Range; (6)Internal Regulator Provides a Stable 5-V Reference Supply With 5% Tolerance; (7)Circuit Architecture Allows Easy Synchronization.

SPS250A power supply 2SC2625

A SMPS I take on trips I forgot is NOT auto voltage sensing on input and was still set to 110V after recent US trip.

Pretty obviously the power transistors got fried and rather than junk it I thought I should fix it

This is dealing with mains voltage so do not do this unless you know what you are doing as the voltages are lethal.

It took a bit of digging to find the circuit diagram (thought it was on the pdf that came with it), still haven't found it exactly but this is very similar except mine appears to run the fan full all the time instead of having a fan control board on the lower right here.


These power supplies are widely in use and all are called SPS250A in the name and are all made in China under various names... so if yours has SPS250A in the name and looks like mine then chances are it is the same but no responsibility if it is not, use information at own peril (and this is running at mains voltage which can kill so do not do this without a healthy respect for high voltages).

The two NPN power transistors 2SC2625 were removed still attached to their heatsink.


Note all the common mode filtering on the input side (top right corner).
Mine has had the right hand transistor crater and the other is short circuit between the pins.

Anyway suffice to say power supply can be easily repaired.

I hear that it might make sense to replace the 2Sc2625 10A versions with 2Sc3220 which are 15A versions but I would source them in HQEW.net  .