12V to 120V DC DC Converter Circuit

Here is a simple DC DC converter schematic using a saturation-limited to push-pull converter. DC converter can be used to power the VCR from a car battery and glow plug light aircraft models from a 12V battery starter.

As a final amplifier of the DC DC converter is a pair of transistor MJE2955 and 2SC945 as oscillator to apply sufficient bias to the final amplifier transistors.

The 2SC945 is a bias switch for startup. When applying 12V power, this transistor applies enough bias to the power transistors to get the oscillation started. Soon later, the 100uF capacitor charges up, the transistor goes off, and the power transistors self-bias into cut-off, such that cross-conduction is eliminated. After removing power, the 6k8 resistor discharges the bias timing capacitor, as otherwise the circuit would be unable to restart!

The secondary rectifiers are ultrafast diodes. These are NOT 1N4007! And the 220nF capacitors for the secondary filter are no typos; the diodes deliver almost pure DC, since the oscillation waveform is square, so only some noise filtering is needed. No electrolytics are necessary here.

DC DC Converter

Note the filters at both input and output, using ferrite cores. These are necessary to avoid polluting your environment with RF noise! Using these filters, and joining the input and output negative leads, this converter is very quiet and does not cause any problem in my combined HF, VHF and UHF station.

All ferrite cores (for the transformer and for the noise filters) are manufactured by Amidon Associates, and can be ordered directly from them in small quantities. Look for Amidon on the web. The 77-material core used for the transformer is less than ideal. A square-loop ferrite would work more efficiently! This one gets really warm, operating in saturation mode at 25 kHz. But it has worked well enough for two years now. The filter cores, on the other hand, are well chosen, so try to use the exact ones.

For all windings, the schematic states the number of turns. “7t” means 7 turns. As the transformer is quite small for the involved power, use as thick a wire as you can fit, leaving about half of the space for the 2×7 turns primary winding, and the other half for the secondary, while the feedback winding can be made from very thin wire.

The transistors do not need any heat sinks. They are large enough without, and they need to dissipate little heat!

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The self protection can avoid the happening of over voltage

The self protection can avoid the happening of over voltage for cell phone jammer .
Domestic mobile Internet into the outbreak, followed by the huge market potential is attracting people of insight. With speeds faster and faster, more powerful mobile terminals, a number of new mobile Internet applications have emerged.
Here are some examples of the Internet do a better job abroad, you can share with you. This is a combination of cell phone location Foursquare is more characteristic, and it is a portable product, and its social, as is the interaction of social contact, and phone and are one to one, and it anytime, anywhere and people can connect together, so it is the location for a successful service. ShopSavvy is a class e-commerce applications, it is to phone all the available features are integrated in one, it is convenient to be able to scan some bar codes Camera, then this product is identified, because the phone is a social network, connect to the network can get more information, one can check information on the Internet, on the other hand it also combines a lot of location information, mobile devices have a joint position, it can to find you around the store price of this product What about, then marked on the map. The cooling fan is specially made for cell phone jammer .On the other hand, it is the users information to add into the evaluation, this product is the phones various functions applied to an extreme. Layar is a location-based services, is a mobile browser, according to the location of cell phone GPS to determine to determine the appropriate number of points of interest nearby, near the information presented in the information integration of these mobile phones. This radar can see through the inside of some nearby points of interest, points of interest and your small number of entities from the above point that out, and then click into the details later, such as the nearby McDonalds to see if there is no coupon, it information to coupons will be displayed, on the one hand a lot of information together and on the other hand is a one-stop, or even an end to end service, from initial inquiry to final a phone call, even after integration of e-commerce functions will in them. That is based on the user experience of mobile Internet, it is necessary the integration of multiple applications. Mobile application development is the need to tackle the key issues, we must find the real applications to meet user needs, large vendors have time to find a little place of concern, with a small adaptation to user needs the application to value. For example, read the industry chain for mobile phone operators can book through the publishing entities to develop games, shooting film, so as to gradually increase in the mobile phone industry chain read influence. In addition, the home market for China Mobile has strategic significance, should develop innovative end products, integrated information service platform to build the family, the family will be introduced to various types of services. Also, the development of mobile Internet for the digital entertainment industry provides opportunities for interactive entertainment market has great potential.

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