Diagram Diagosis

Showing posts with label converter. Show all posts

Monday, September 30, 2013

12V Glow Plug Converter

Most small internal-combustion engines commonly used in the model-building world use glow plugs for starting. Unfortunately, glow plugs have an operating voltage of 1.5 V, while fuel pumps, starter motors, chargers and the like generally run on 12 V. This means that a separate battery is always needed to power the glow plug. The standard solution is to use an additional 2-V lead storage battery, with a power diode in series to reduce the voltage by approximately 0.5 V. However, this has the annoying consequence that more than 30 percent of the energy is dissipated in the diode. Naturally, this is far from being efficient. The converter presented here allows glow plugs to be powered from the 12-V storage battery that is usually used for fuelling, charging, starting and so on.

A car battery can also be used as a power source. Furthermore, this circuit is considerably more efficient than the approach of using a 2-V battery with a series power diode. The heart of the DC/DC converter is IC1, a MAX 1627. The converter works according to the well-known step-down principle, using a coil and an electrolytic capacitor. Here the switching stage is not integrated into the IC, so we are free to select a FET according to the desired current level. In this case, we have selected a 2SJ349 (T1), but any other type of logic-level FET with a low value of RDSon would also be satisfactory. Of course, the FET must be able to handle the required high currents. Diode D1 is a fast Schottky diode, which must be rated to handle the charging currents for C2 and C3. This diode must also be a fairly hefty type. The internal resistances of coil L1 and capacitors C2 and C3 must be as low as possible. This ensures efficient conversion and prevents the components from becoming too warm. The resistor network R2/R3 causes 87 percent of the output voltage to be applied to the FB pin of IC1.

This means that an output voltage of 1.5 V will cause a voltage of approximately 1.3 V to be present at the FB pin. The IC always tries to drive the switching stage such that it ‘sees’ a voltage of 1.3 V on the FB input. If desired, a different output voltage can be provided by modifying the values of R2 and R3. When assembling the circuit, ensure that C5 and C1 are placed as close as possible to IC1, and use sufficiently heavy wiring between the 12-V input and the 1-5-V output, since large currents flow in this part of the circuit. A glow plug can easily draw around 5 A, and the charging current flowing through the coil and into C2 and C3 is a lot higher than this!

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Wednesday, May 1, 2013

Short Wave Converter

http://users.belgacom.net/hamradio/schemas/50mc_Converter_on1dht.gif

This short-wave converter, which doesn’t have a single coil requiring alignment, is intended to enable simple medium-wave receivers to be used to listen to short-wave signals. The converter transforms the 49-m short-wave band to the medium-wave frequency of 1.6 MHz. At the upper end of the medium-wave band, select an unoccupied frequency that you want to use for listening to the converted short-wave signals. Good reception performance can be obtained using a wire antenna with a length of one to two metres.

The converter contains a free-running oscillator with a frequency of around 4.4 MHz, which is tuned using two LEDs (which act as variable-capacitance diodes!) and a normal potentiometer. The frequency range is set by adjusting the emitter current using a 1k trimpot. The oscillator frequency depends strongly on the operating point. This is due to the combination of using an audio transistor and the extremely low supply voltage. Under these conditions, the transistor capacitances are relatively large and strongly dependent on the operating point. The second transistor forms the mixer stage.

If you calculate the resonant frequencies of the tuned circuits, you will obtain 6.7 MHz for the antenna circuit and 1.7 MHz for the output circuit. Additional transistor capacitance and the effects of the coupling capacitors shift each of the resonant frequencies downward. The tuned circuits are relatively heavily damped to obtain bandwidths that are large enough to allow the circuit to be used without any specific alignment. The results are good despite the low collector–emitter voltage of around only 0.6 V, due to the fact that only a modest amount of mixer gain is necessary. The entire circuit also draws less than 1mA.

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Thursday, April 11, 2013

6 to 12 Volt Converter

Below its a converter circuit voltage from 6 Volt to 12 Volt DC.

6 Volt to 12 Volt DC

Part List :
R1, R4 2 .2K 1/4W Resistor
R2, R3 4.7K 1/4W Resistor
R5 1K 1/4W Resistor
R6 1.5K 1/4W Resistor
R7 33K 1/4W Resistor
R8 10K 1/4W Resistor
C1,C2 0.1uF Ceramic Disc Capacitor
C3 470uF 25V Electrolytic Capcitor
D1 1N914 Diode
D2 1N4004 Diode
D3 12V 400mW Zener Diode
Q1, Q2, Q4 BC547 NPN Transistor
Q3 BD679 NPN Transistor
L1 See Notes
Notes
1. L1 is a custom inductor wound with about 80 turns of 0.5mm magnet wire around a toroidal core with a 40mm outside diameter.

2. Different values of D3 can be used to get different output voltages from about 0.6V to around 30V. Note that at higher voltages the circuit might not perform as well and may not produce as much current. You may also need to use a larger C3 for higher voltages and/or higher currents.

3. You can use a larger value for C3 to provide better filtering.

4. The circuit will require about 2A from the 6V supply to provide the full 800mA at 12V.

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Wednesday, April 10, 2013

Simple 220V SMPS Buck Converter Circuit Using VIPer12A IC

The presented article explains a simple buck converter or an SMPS circuit using the IC VIPer12A from STMicroelectronics. The circuit uses negligible number of external components yet is able to operate directly from mains AC input.

Looking at the given circuit diagram we see that the input stage incorporates a surge limiting resistor which quite acts like a fuse, a diode for rectifying the AC, and an LC filter network for further filtration of the DC riples.

The LC filter employed here ensures better DC stabilization and enhanced EMI response.

The capacitor Cin1 may be introduced for further reinforcing the EMI functionality.

The IC VIPer12A becomes the main PWM processor device which single handedly performs the entire buck conversion in the circuit.

The main specifications of the configuration may be understood as follows:

AC input voltage Vinac 80 - 285Vac
Output current Iout 30mA
Output current Iout2 50mA
Output voltage Vout1 +24±10%V
Output voltage Vout2 +5V±5%
Switching frequency 60 kHz
Output Power ~ 1W

The circuit facilitates two outputs, rhe 24V output is achieved through a buck converter configuration while the 5V output via fly back mode.

The feedback voltage to the IC is acquired from Vout1 for the required regulation of the output, this supply is also applied to the IC Vdd pin.

The above wiring becomes possible by using a single high voltage diode and just one capacitor, to be precise D1 and C3, making the connections and costing much simpler.

The employed inductor L consists of two windings which are coupled across with each other over a common ferrite core.

The winding are done through appropriate turn ratios, where N1 = 200 turns and N2 = 60 turns. Both these are wound over a PANASONIC ELC10D152E ferrite core material.

Zener diodes z1 and z2 are installed in order to safeguard the outputs against over voltages.

A dummy load resistor is fixed across Vout1 so that appropriate regulation can be executed over both the outputs during open load situations.

Though the addition of the above resistor affects the efficiency a bit, it superbly improves voltage regulation response of the circuit.

The rectifier diodes fixed at the output are fast response fast recovery types. D1 is a high voltage diode as it might be subjected to high reverse voltages delivered by the DC bus voltage...... D2 is a normal diode.

Parts List for the proposed simple SMPS buck converter circuit:

Rr 10W 1/2W
Rf 10KW 1/4W
Rburden 4.7kW 1/4W
Cin 4.7 μF, 450V Electrolytic Capacitor
C1 33 μF, 50V Electrolytic Capacitor
C2 100 μF, 16V Electrolytic Capacitor
C3 1 μF, 25V Electrolytic Capacitor
C4 22 nF Ceramic capacitor
Dr Diode 1N4007
D1 Diode BA159 (fast)
D2 Diode 1N4148 (fast)
D3 Diode 1N4004
Dz 22V Zener
Dz1 27V Zener
Dz2 5.6V Zener
L 1.5 mH
Lf 470 μH Inductor
IC1 STMicroelectronics VIPer12ADIP

PCB Design and Component Layout of the above explained SMPS buck converter circuit using IC VIPer12A

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Tuesday, April 9, 2013

4 Bit Analogue to Digital Converter

The operation of the converter is based on the weighted adding and transferring of the analogue input levels and the digital output levels. It consists of comparators and resistors. In theory, the number of bits is unlimited, but each bit needs a comparator and several coupling resistors. The diagram shows a 4-bit version. The value of the resistors must meet the following criteria:

R1:R2 = 1:2;
R3:R4:R5 = 1:2:4;
R6:R7:R8:R9 = 1:2:4:8.

The linearity of the converter depends on the degree of precision of the value of the resistors with respect to the resolution of the converter, and on the accuracy of the threshold voltage of the comparators. This threshold level must be equal, or nearly so, to half the supply voltage. Moreover, the comparators must have as low an output resistance as possible and as high an input resistance with respect to the load resistors as feasible. Any deviation from these requirements affects the linearity of the converter adversely.

Circuit diagram:

4-Bit Analogue to Digital Converter Circuit Diagram

If the value of the resistors is not too low, the use of inverters with an FET (field-effect transistor) input leads to a near-ideal situation. In the present converter, complementary metal-oxide semiconductor (CMOS) inverters are used, which, in spite of their low gain, give a reasonably good performance. If standard comparators are used, take into account the output voltage range and make sure that the potential at their non-inverting inputs is set to half the supply voltage. If high accuracy is a must, comparators Type TLC3074 or similar should be used. This type has a totem-pole output. The non-inverting inputs should be interlinked and connected to the tap of a a divider consisting of two 10 kΩ resistors across the supply lines. It is essential that the converter is driven by a low-resistance source. If necessary, this can be arranged via a suitable op amp input buffer. The converter draws a current not exceeding 5 mA.

Source :www.ecircuitslab.com

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