Sunday, August 31, 2014
Simple FM transmitter circuit 88 108MHz
This is simple transmitter schema diagram.This schema has some what good coverage.To tune this schema use 88MHz-108MHz radio.This schema can be operated with 9-12V power supply.This schema needs 30mA.
Note
#In some countries transmitters have been banned.so dont misuse this schema.We just wanted to give you an extra knowledge about it.If somebody used this for unnecessary things we cant get the responsibility of it.
Power Amplifier Class A circuit
This is a design schematic Class A power amplifier . This is a close as possible in operating parameter the Under Classes is class B , to aid comparison ; in particular the NFB factor remains 30dB at 20 kHz. The front end is similiar to class B amplifier. This circuit uses a standart quasi output. This may be replaced by a CFP stage without problems. In both cases the distortion is extremely low, but gratifyingly the CFP proves even better than quasi , confirming the simulation results for output stages in isolation.
About Class-A amplifier , in this class is the highest class from another class. Classes below begin from AB to Class S. In a Class-A amplifi er current fl ows continuously in all the output devices, which enables the nonlinearities of turning them on and off to be avoided. They come in two rather different kinds, although this is rarely explicitly stated, which work in very different ways. The fi rst kind is simply a Class-B stage (i.e. two emitter-followers working back to back) with the bias voltage increased so that suffi cient current fl ows for neither device to cut off under normal loading.
The great advantage of this approach is that it cannot abruptly run out of output current; if the load impedance becomes lower than specifi ed then the amplifi er simply takes brief excursions into Class-AB, hopefully with a modest increase in distortion and no seriously audible distress.
This is schematic power amplifier class A below :
About Class-A amplifier , in this class is the highest class from another class. Classes below begin from AB to Class S. In a Class-A amplifi er current fl ows continuously in all the output devices, which enables the nonlinearities of turning them on and off to be avoided. They come in two rather different kinds, although this is rarely explicitly stated, which work in very different ways. The fi rst kind is simply a Class-B stage (i.e. two emitter-followers working back to back) with the bias voltage increased so that suffi cient current fl ows for neither device to cut off under normal loading.
The great advantage of this approach is that it cannot abruptly run out of output current; if the load impedance becomes lower than specifi ed then the amplifi er simply takes brief excursions into Class-AB, hopefully with a modest increase in distortion and no seriously audible distress.
This is schematic power amplifier class A below :
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| Click image to view larger |
The operation of current regulator TR13 , TR15 , TR 16 has already been described. The reference used is a National LM385/1.2 Its output voltage is fixed at 1.233 V nominal ; this is reduced approximately 0.6V by 1k - 1k divider . The circuit is the best for me , because is loudly , and does not vibrate the speakers leaves , softly sound , and low noise . And i like it .,., :)
For the hobby electronics especially in the amplifier , is suitable to be tried.
TDA1552Q 2 x 22 W BTL stereo car radio power amplifier
GENERAL DESCRIPTION
The TDA1552Q is an integrated class-B output amplifier in a 13-lead single-in-line (SIL) plastic power package. The circuit contains 2 x 22 W amplifiers in Bridge Tied Load (BTL) configuration. The device is primarily developed for car radio applications.
Features
- Requires very few external components
- High output power
- Low offset voltage at outputs
- Fixed gain
- Good ripple rejection
- Mute/stand-by switch
- Load dump protection
- AC and DC short-circuit-safe to ground and VP
- Thermally protected
- Reverse polarity safe
- Capability to handle high energy on outputs (VP = 0 V)
- Protected against electrostatic discharge
- No switch-on/switch-off plop
- Low thermal resistance
- Flexible leads.
Circuit diagram:
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| Circuit diagram for TDA1552Q 2 x 22 W BTL stereo car radio power amplifier |
100w audio amplifier
General description:
All resistors are standard metal film 250mW except: R1/3/4/7, these are 2W metal film, and the 0.22ohm beeing 5W. Around R7 is wounded a 0.6mm isolated (enamelled) copper wire forming the output coil. (~12 windings) For c19 i used 470uf/16v, all other electrolytics 63v. The 10/100/330pF should be mica-caps. The 100nf and 47nf is recommended to be Wima MKS2 (or better), also for C1 i suggest Wima MKS2, 4.7uf is enough. For Trimpot i use a Piher. The MPSA18 can be substituted by BC550C, for all other parts i do not recommend changes, especially the feedback network (r29/30) should be kept unchanged, feedback compensation is very delicate for this circuit ! Be careful when substituting the MPSA18 with BC550C, the pinout is reversed between these 2 transistors !!! The bias is adjusted via the trimpot (R22). Recommended bias is 55ma, resulting in 12mv across a single 0.22ohms or 24mv across both 0.22ohms. Connect a DMM to the upper wires of these resistors and adjust trimpot until DMM reads wanted voltage.
Features:
THD: ~0.005% (measured) simd: 0.002%
Power into 8ohm: 60 watts
Power into 4ohm: 100 watts
Gain: 32dB (~1:40) full output at 0.7v input (0.5v rms)
Feedback: 57dB
GainBandWidth: ~400Mhz
Slewrate: ~20v/us (symetrical)
Supply voltage: +/- 36v
Biasing: 55ma, ~12mv across a single 0.22 ohm
Measurings:The measuring setup itself is far from perfect, but gives a good idea !
Frequency response: 3.2hz to 145khz (-1db) using 4.7uf input cap
Phaseshift at 10khz: <3°
More will follow !
Circuit Diagram:
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| 100w audio amplifier circuit diagram |
Layout Diagram:
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| 100w audio amplifier layout diagram |
Partlist:
Device | Qty | Value | Notes |
Q1,Q2 | 2 | MPSA18 | can be substituted by BC550C (pins reversed !) |
Q7,Q8 | 2 | BC546B | or maybe 2n5551 (pins reversed !) |
Q3,Q9 | 2 | 2N5551 | OnSemi/Fairchild/Philips |
Q4,Q5,Q12 | 3 | 2N5401 | OnSemi/Fairchild/Philips |
T1 | 1 | BD139 | or bd135, bd135-16 |
U$5 | 1 | MJE15030 | OnSemi |
U$6 | 1 | MJE15031 | OnSemi |
U$3 | 1 | MJL3281A | OnSemi |
U$4 | 1 | MJL1302A | OnSemi |
Device | Qty | Value | Notes |
C14 | 1 | 10pF (has been 22pF) | Mica |
C2,C7 | 2 | 100pF | Mica |
C3,C4 | 2 | 330pF | Mica |
C18 | 1 | 47nF | Wima MKS2 |
C5, C6, C10, C11, C16, C17, C20 | 7 | 100nF | Wima MKS2 |
C1 | 1 | 10uF (4.7uF also fits) | Wima MKS2 |
C8,C9 | 2 | 100uF | Electrolytic 63v (at least 40v) |
C19 | 1 | 470uF | Electrolytic 16v |
C12,C13 | 2 | 1000uF | Electrolytic 63v (at least 40v) |
Device | Qty | Value | Notes |
R27,R28 | 2 | 0R22 | 5Watts |
R1, R3 | 2 | 1R2 | 2Watts metal film |
R4 | 1 | 4R7 | 2Watts metal film |
R7 | 1 | 10 | 2Watts metal film |
R2 | 1 | 10 | 250mW metal film |
R8, R9 | 2 | 22 | 250mW metal film |
R31, R32 | 2 | 47 (have been 22) | 250mW metal film |
R26 | 1 | 33 | 250mW metal film |
R10 | 1 | 68 | 250mW metal film |
R15,R17 | 2 | 150 | 250mW metal film |
R11 | 1 | 220 | 250mW metal film |
R24,R30 | 2 | 499 (or 500) | 250mW metal film |
R5,R6 | 2 | 680 | 250mW metal film |
R13,R23 | 2 | 2k | 250mW metal film |
R12,R14,R29 | 3 | 22k | 250mW metal film |
R18,R20 | 2 | 47k | 250mW metal film |
R22 | 1 | 1k pot | Piher, small (470ohm might be better) |
Device | Qty | Value | Notes |
F1,F2 | 2 | 2.5T Fuse | Slow blow |
F1,F2 | 2 | --- | Fuse holder |
L1 | 1 | --- | 0.6mm isolated (enamelled) copper wire wounded around R7 forming the output coil. |
Saturday, August 30, 2014
Make an Efficient LED Emergency Light Circuit
The article describes a very simple homemade emergency light schema that can be used during power failures and outdoors where any other source of power might be unavailable. The schema uses LEDs instead of incandescent lamp, thus making the unit very power efficient and brighter with its light output. Moreover, the schema employs a very innovative concept especially devised by me which further enhances the economical feature of the unit.
We know that LEDs require a certain fixed forward voltage drop to become illuminated and it is at this rating when the LED is at it’s best, that is voltages which is around its forward voltage drop facilitates the device to operate in the most efficient way.
As this voltage is increased, the LED starts drawing more current, rather dissipating extra current by getting heated up itself and also through the resistor which also gets heated up in the process of limiting the extra current.
If we could maintain a voltage around an LED near to its rated forward voltage, we could use it more efficiently. That’s exactly what I have tried to fix in the schema.
Since the battery used here is a 6 volt battery, means this source is a bit higher than the forward voltage of the LEDs used here, which amounts to 3.5 volts. The extra 2.5 volts rise can cause considerable dissipation and loss of power through heat generation.
Therefore I employed a few diodes in series with the supply and made sure that initially when the battery is fully charged; three diodes are effectively switched so as to drop the excess 2.5 volts across the white LEDs (because each diode drop 0.6 volts across itself).
Now as the voltage of the battery drops, the diodes series are reduced to two and subsequently to one making sure only the desired amount of voltage reaches the LED bank.
In this way the proposed emergency lamp schema is made highly efficient with its current consumption, and it provides backup for a much longer period of time than what it would do with ordinary connections.
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