Category: Electronics


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The transistor MMBT3904 is designed for general purpose amplifier applications. It is housed in the SOT–323/SC–70 which is designed for low power surface mount applications.

 Parametrics:
MMBT3904 maximum ratings: (1)Collector–Emitter Voltage VCEO: 40 Vdc; (2)Collector–Base Voltage VCBO: 60 Vdc; (3)Emitter–Base Voltage VEBO: 6.0 Vdc; (4)Collector Current — Continuous IC: 200 mAdc.

Features:
MMBT3904 features: (1)Total Device Dissipation TA = 25℃ PD 150 mW; (2)Thermal Resistance, Junction to Ambient RθJA 833 ℃/W; (3)Junction and Storage Temperature TJ, Tstg –55 to +150 ℃.

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Previous LED lamps with a constant voltage power supply, do not understand the performance of the LED, small light in accordance with the manufacturers to the data of each bead to give to 20MA, weve tested, lamp beads, always burn, and before we know the manufacturers The data is not reliable, we reduce the current use. It was in 2002, do MR16 bulb, billboards and the like applications. I began in 2007 to do the constant current driver, what HV9910, PT4107, PT6901, SN3910, IR, the test more, but the first is the QX9910, some goods, but there are many defective products QX9910 aging The product is also less stable, often have flashing lights, there are still some remaining souvenirs. In my view, in order to do the driver first to get a good chip.

In 2007 when the original, constant current IC is difficult to find, the price of your bizarre, an HV9910 8 yuan, an IRs S2540 25 yuan, in fact, a half-bridge chip, used to intimidate people, but also Japans chip is also used to intimidate, in fact, is the general constant voltage ICs, boring chip away a very long detour, and seriously affected the progress.

HV9910 series in the second generation IC is also very popular, but for technical reasons, the high pressure directly into the IC, easy to blow. Later came out a lot of imitation, imitation is the best SMD802 multiple output short circuit protection, have been widely adopted, with the replacement, this IC is now obsolete.

LM335Z MEASURING TEMPERATURE

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I decided to try another schematic for measurement of the temperature this time with LM335Z low cost sensor.

LM335Z have 0V at absolute zero temperature i.e. -273.2C and it’s output increase with 10mV/C so at room temperature the sensor will output about 2.73V

to measure this temperature with Duinomite is piece of cake:

10 SETPIN 1,1  ’setup PIN(1) as analog input

20 PRINT “ROOM TEMPERATURE IS”;PIN(1)*100-273

the problem is that PIC32 Analog input can’t take more than 3.3V on it’s ADC, so maximal temperature measured will be 57C well this still is enough for some application, but why not measure the complete temperature range -40C+100C ? (if you use LM135 the range will be -55+150C)

to do this we have to add resistor ladder which to divide the output voltage, TassyJim uses 18K/27K in his project posted at TheBackShed forum, and I found his 0.6 round divider as nice so decided to use same values.

then  I wrote this simple code:

10 SETPIN 1,1

20 PRINT “ROOM TEMPERATURE IS: “; PIN(1)*166.7-273

RUN

ROOM TEMPERATURE IS: 24.5645

it’s really not so hot in my office so I start thining what is wrong and I found it – I used 5% resistors as I had no preciese resistors so the voltage divider was not exactly 0.6 but something else and was mixing my result, no problem I took preciese ohm meter and measured R2 and R3 the values are:

R2 = 17 860 ohm

R3 = 26 600 ohm

aha so the voltage divider is 0.59829! and the coefficient I have to use in the formula is 100/0.59829 = 167.1

I corrected the formula:

20 PRINT “ROOM TEMPERATURE IS: “; PIN(1)*167.1-273

RUN

ROOM TEMPERATURE IS: 23.6145

so with not preciese resistors I got preciese result because DM-BASIC have no problems to work multiply real numbers .

ImageAs everyone knows, connecting technology in parallel has already become key technology of realizing distributed power system of high-power, but because every module characteristic of connecting the power in parallel is not totally unanimous, the module of the output with high voltage may be born and supported more, but some module may lighter by year, even empty load run, result lead to the fact share electric current many module heat stress to be loud, have reduced the working dependability of the whole power. With the development of electronic system, the requirements for power dependability, efficiency and power density are higher and higher, so it is necessary to adopt a kind of effective flowing and controlling the scheme, guarantee the output electric current of the whole power system is shared equally according to the output ability of each unit module, in this way, not only can give full play to the output ability of the power module of unit guarantee the working dependability of each unit power, but also can.

Against become main circuit for hand in and frank – hand in voltage type, it commutates sides to be controllable type as single-phase diode. This way not only controls simply but also have a higher power factor systematically. In order to reduce the device volume, reduce the harmonic wave, improve electric current wave form quality. The power component adopts module PM20CSJ060 of the third generation of intellectual power of Mitsubishi Electric Company of the high switch frequency against turning into. Module this unify encapsulation for six, inside the intersection of three-phase and bridge the intersection of circuit and structure, inside integrate at a high speed low the intersection of IGBT and chip of consumption and drive, protect the circuit. In addition, this module also integrates overheatedly and owes and presses and locks and protects the circuit, make the dependability of the system further improved . Space of six routes vector signal SVPWM that LF2407 chip outputs on the control circuit is realized that isolates IPM to drive by the photosensitive resister 6N136, and then commutate the direct current after straining the wave and press and go against to turn into necessary high-frequency alternating current and drive the compressor of air conditioner of permanent magnetism.

There is electric current that measures the circuit in the system, adopt the sensor of Hall’s electric current to measure the magneto A, C two phase forever, utilize, sample resistance and then and many stages transport show, deal with for simulation voltage signal that change among 0- 5V the intersection of electric current and signal, the pin links with integrating outside A/D converter in LF2407. Because of not having initial position where position sensor technology can’t know the rotor, the magneto works under having position sensor state after only starting too forever, so realize the detection of the initial position of the rotor with the photoelectricity type rotation encoder. Realization comes by the incident managing device of LF2407 in other protection circuit, once break down systematically, the break procedure solidifying in slice exports cutting off systematic SVPWM automatically, until the trouble disappears and resets systematically.

This text foundation permanent magnetism synchronous motor vector controls the requirements of principle and frequency conversion air conditioner, have developed a set of brand-new frequency conversion air conditioner control systems based on DSP. SVPWM control signal produced with six PWM complete comparators of LF2407 can realize that control the frequency conversion of the synchronous motor of permanent magnetism. This air conditioner of control systems have fully utilized superstrong real-time computing capability and some integrated devices of LF2407, make the whole system simple in construction, products development period is short, highly reliable.

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Electronic Circuit Diagram TV vertical Using LA7841, LA7840

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Electronic Circuit Diagram TV vertical Using LA7841, LA7840 Basic Electronic Circuits – Datasheets

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Electronic Circuit Diagram TV vertical Using LA7841, LA7840

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The LM158 series consists of two independent, high gain,internally frequency compensated operational amplifiers which were designed specifically to operate from a single power supply over a wide range of voltages. Operation from split power supplies is also possible and the low power supply current drain is independent of the magnitude of the
power supply voltage.

Application areas include transducer amplifiers, dc gain blocks and all the conventional op amp circuits which now can be more easily implemented in single power supply systems. For example, the LM158 series can be directly operated off of the standard +5V power supply voltage which is used in digital systems and will easily provide the required
interface electronics without requiring the additional ±15V power supplies.

The LM358 and LM2904 are available in a chip sized package (8-Bump micro SMD) using National’s micro SMD package technology.

 ImageSSM2164 VCF AND MODULAR WORKSTATION

1. GATE INPUT–> THIS REQUIRES A 0-5V RANGE GATE SIGNAL,

THESE ARE FROM SEQUENCERS, OR MIDI-2-CV CONVERTERS.
2. ENV OUT–> THIS IS THE ANALOG ENVELOPE AR OUT. YOU

HAVE TO PATCH THIS TO CV IN OR FM IN TO MODULATE THE

FILTER WITH THIS. YOU CAN ALSO MODULATE YOUR EXTERNAL

GEAR WITH THIS. IT IS BASED ON -/+5V RANGE. SO IT IS

SAFE TO PATCH TO YOUR GEAR.
3.AIN(1) AND AIN(2) ARE AUDIO INPUTS. SOUND GOES FIRST

TO THE PRE-AMP(BOOSTER) THEN TO THE AIN LVL KNOB.
4.CV IN–>THIS IS A CONTROL VOLTAGE INPUT. PLUG AN

ANALOG LFO, AR ENV, VCO SIGNAL ETC.
5.FM IN–> THIS IS THE SAME AS THE CV IN BUT THIS IS BI

-POLAR GIVING YOU +/- SWEEP. CENTER IS ZERO VALUE.
6. EXTREME FM–> THIS IS SO THAT YOU CAN USE “LINE

LEVEL” SIGNALS TO MODULATE THE FILTER OR YOUR OTHER

ANALOG GEAR. THIS IS JUST A DIRECT OUT COMING FROM AIN

(1) BOOSTER(1). SO WHAT YOU DO IS PLUG IN YOUR FAVORITE

DRUM MACHINE OR VIRTUAL ANALOG IN AIN(1), TURN UP THE

BOOSTER TO AMPLIFY BUT HAVE AIN(LVL)1 AT ZERO SO YOU

DON’T HEAR IT. NOW PATCH FROM EXTREME FM OUT TO CV OR FM

INPUT. TURN THE FILTER ALL YOU WILL HEAR IT MODULATE TO

YOUR EXTERNAL LINE LEVEL SOURCE.
7. FILTER OUT–>THE IS THE UNBALANCED SIGNAL THAT GOES

TO YOUR MIXER OR AMP.
8. LFO OUT–>THE IS THE LFO OUTPUT. IT IS A SLOW

OSCILLATOR SO YOU CAN PATCH IT TO AN AIN TO HEAR IT IF

YOU WANTED TO MAKE A PORTABLE SOUND BOX.

BY ALL MEANS TURN UP THE REZ TO SELF-OSCILLATE AND GET A

CLEAN SINE WAVE. THIS IS ONE OF THE BEST ONES I HAVE

TDA7000 FM Receiver / TV Tuner

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This simple one chip FM receiver / TV tuner will allow you to receive frequencies from 70 up to 120MHz. With this small receiver it is possible to pickup TV stations, entire 88 – 108MHz FM band, aircraft conversation and many other private transmissions. It is a perfect companion to any FM Transmitter especially if FM band in your area is very crowded. TDA7000 receiver offers very good sensitivity therefore it will even allow you to pickup weaker signals that cannot be heard on conventional FM receivers.

A neat feature of presented TDA7000 FM receiver is a voltage controlled oscillator similar to TV tuners that are used in television sets. Frequency is tuned by varying the input voltage to the oscillator. The advantage of this type of oscillator is that you can use regular 100K potentiometer to precisely tune to a given broadcast. Tuning can be performed much quicker and precisely than by using a trimmer (variable capacitor). Trimmers will also shift the frequency as you touch them where potentiometer will not. Trimmer also needs to be placed on receiver’s PCB to minimize the stray capacitance where potentiometer can be conveniently placed anywhere you want because it will not be affected by any external capacitance.

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Receivers and Antennas

In typical radio listening (like AM, FM, and shortwave), you tune the receiver to a radio frequency that is much higher than the human hearing range. The receiver demodulates this high-frequency signal to recover the sound that was embedded in it. VLF receivers are much simpler, and not really “radios” at all. They simply translate electromagnetic waves into sound … literally a bare wire feeding a high-gain audio amplifier! (Actually there are 2 types of VLF receiver: E-field and B-field. I’m mostly discussing E-field.)

The INSPIRE project offers a VLF receiver in kit form, with field-proven amenities like filters and a built-in headphone amplifier. (They also have great general info on VLF phenomena.) Others are available either pre-built or as kits.

The Bike Loop is a (b-field) antenna and receiver combo built by Roberto and Claudio Parmigiani (IW2FER), Gabriele Seleri (IW2DWN). The antenna is made of bicycle rims!

I built a stereo pair of the “Super-Tiny VLF Receiver” designed by Charles Wenzel (www.techlib.com). It’s incredibly simple (3 parts!) and runs on “plug-in power” provided by most small flash recorders.

Construction Notes

I assembled mine in “dead-bug” style, super-sloppy with parts substitutions based on what I had lying around. It works wonderfully. (My FETs were 2SK170′s.)
A metal box would be ideal, but plastic with foil-tape shielding worked OK.

S8050 Transistor

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The transistor I bought from en electronic market has labeling as “S8050 D 331″. I used a multimeter to measure its hfe value and it shows 186 (varying between 186 and 188).

There are hfe1, hfe2, hfe3 for  this S8050 transistor and for each there are associated MIN, TYP and MAX value. for hfe1and hfe3 there are only a MIN value, but for hfe2 the values MIN, TYP and MAX are all exist. Why is the difference?
What does hfe1, hfe2 and hfe3 mean? If they all exist, do I still have a unique value? Which one of them correspond to the 186 value which I got from the multimeter?
Why for each of them there are a range of values (MIN, TYP, MAX)?  If the hfe has, for example like hfe2, MIN value as low as 100 and MAX as high as 400, then how can I know exactly which hfe value the transistor will operate on, and consequently, how should I design the circuit (resistance values, saturation mode, etc.)?

The forward current gain of a BJT varies depending on the collector current. This manufacturer has provided information on Hfe at three different operating currents that they call 1, 2, and 3.

Manufacturers generally only provide min and max characteristics for parameters that they actually test on each device that they ship. Other information is provided so that the user can get a sense of how the device may behave in various circuits.

The meter you are using probably tests beta or Hfe at a relatively low collector current, perhaps around 1mA. The instructions for the meter may provide this information.