Showing posts with label circuits. Show all posts
Showing posts with label circuits. Show all posts
Thursday, November 20, 2014
X Ray Protector Circuits
A protector system that is applied at the beginning of the television technique, therefore most often found on old aircraft models. If the high voltage anode of the picture tube flyback tranfo exceed the permitted limit, the picture tube can generate x-rays from the anode and shadowmask are bombarded by electrons at high speed. To avoid this problem then mounted x-ray surge protector circuit , which automatically "horizontal section will be turned off" if the high voltage from the flyback over.
| X-Ray vertical protect |
The workings of x-ray protector:
- High voltage flyback sampled (generally taken from the pin-heater), rectified and is derived using a divider (devider) that uses a resistor-type high-precision resistor. Sample voltage is used to determine whether the condition is normal flyback voltage or over.
- A "zener diode" as a voltage sensor connected to the sample. In normal conditions the amount of the sample voltage is below the zener voltage of diode so that the condition "off" or is not transparent.
- Suppose there is a sudden event increased flyback voltage - the voltage will rise above the sample diode voltage value, which causes the diode "on" or voltage through the diode, which would trigger protectionist active work.
Problems that can lead to x-ray active protector works:
- Damage that causes the power supply voltage B + or incorrect adjustment over
- Resonant capacitor to the collector of transistor HOT off the decline or solder
- Tranfo replacement flyback mounted do not match.
- Damage to one part in the sensor circuit protectors x-ray alone
| X-ray Protect Circuit |
Sunday, August 31, 2014
Phonon Preamplifier Circuits Wiring diagram
In recent years, following CDs introduction, vinyl recordings are almost disappeared. Nevertheless, a phonon preamplifier is still useful for listening old vinyl discs from a well preserved collection. This simple but efficient schema devised for cheap moving-magnet cartridges, can be used in connection with the audio power amplifiers shown in these webpages, featuring low noise, good RIAA frequency response curve, low distortion and good high frequency transients behavior due to passive equalization in the 1 to 20KHz range. Transistors and associated components provide ±18V supply to the op-amp, improving headroom and maximum output voltage.
Phono Preamplifier Circuits Diagram
- R2, R3, R4, R7, R8, C4 & C5 should be low tolerance types.
- Schematic shows left channel and power supply.
- For stereo operation R1, R2, R3, R4, R7, R8; J1; C1, C4 & C5 must be doubled.
- Numbers in parentheses show IC1 right channel pin connections.
Technical data:
Sensitivity @ 1KHz: 2.5mV RMS input for 200mV RMS outputMax. input voltage @ 1KHz:120mV RMS
Max. input voltage @ 10KHz:141mV RMS
Max. input voltage @ 20KHz:127mV RMS
Frequency response @ 1V RMS output: 100Hz to 20KHz ±0.5dB; -0.75dB @ 30Hz
Total harmonic distortion @ 1KHz and 6V RMS output: 0.006%
Total harmonic distortion @10KHz and 1V RMS output: 0.02%
Parts:
R1_________47K1/4W Resistor
R2________100R1/4W Resistor
R3__________6K81/4W ResistorR4_________68K1/4W Resistor
R5,R6_______2K71/4W ResistorR7__________2K21/4W ResistorR8_________39K1/4W Resistor
C1-C3_____100µF25V Electrolytic CapacitorsC4,C5______47nF63V Polyester Capacitors 5% toleranceD1,D2__BZX79C1818V 500mW Zener DiodesIC1_______LM833Low noise Dual Op-ampQ1________BC33745V 800mA NPN TransistorQ2________BC32745V 800mA PNP TransistorJ1__________RCAaudio input socketSaturday, August 30, 2014
Bipolar Power supply for Battery Instruments Circuits Wiring diagram
Bipolar Power supply for Battery Instruments Circuits Diagram. To generate regulated ± 5-V supplies from a pair of dry batteries, the schema of Fig. 1 is commonly used. In order to give protection from inadvertent reverse connection of a battery, a diode in series with each battery would produce an unacceptable voltage drop. The more effective approach is to fit diodes Dl and D2 as shown in Fig. 2, in parallel with each battery.
When the supply is switched off, there is the risk of a reverse bias being applied across the regulators, if there is significant inductance or capacitance in the load schema.Diodes across the regulators prevent damage. When the power supply is switched on, the two switches do not act in unison. There is a probability that one or the other regulators will be latched hard off by the other. To prevent this, D3 and D4 are Zener diodes so that ± 5-V rails are pulled up by the batteries until the regulators establish the correct levels.
Bipolar Power supply for Battery Instruments Circuits Diagram
Sunday, August 10, 2014
LED flasher with Transistor circuits Wiring diagram
These diagram only flash one or two LEDs. This is opposed to the light chaser diagram that can flash four or more. Of course, the simplest LED flasher is simply to use a flashing LED. The problem with that approach is you have no control over the flash rate, but it does have its use for eye catching displays for selling stuff. The diagram below give you that control, plus they can flash two LEDs alternately.
There are many possible applications for the diagram below, especially for kids, who love flashing lights. Heres some possible uses.
- Railroad crossing signal for model railroads.
- Safety blinkers for bicycles, etc.
- Fun stuff for Halloween, like making those plastic Jack-O-lanterns blink (try using ultraviolet LEDs here).
- Christmas decorations.
- Blinkers to locate items in the dark.
Transistor LED flasher
This schema has a lot going for it. For one thing, it only consists of two transistors, two capacitors and four resistors. That also means it consumes very little power. You can control the flash rate by changing the size of the 100k resistors (100k makes for a pretty slow rate). You can also control the duty cycle by using resistors of different values on the two sides. The 470 ohm resistors control the current through the LEDs. Normally you want to limit this to 20mA, but to conserve battery power, you may need to limit it even further. You can also connect several LEDs in series, instead of using only one for each side. With red LEDs (1 per side) and the values shown, the schema draws about 11mA. Heres what the actual schema looks like:
On this schema, the green wires connect to the LEDs, but you can mount them on the actual schema board for some applications. The picture is about twice actual size. Here is an example of the use of this schema:
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