The goal of this project is for me personally to learn a little more about fm transmitters and fm bug making (may the HAM radio gods bless me in this pursuit). The ideal outcome of this project is a very small and full functional FM transmitter that we can stick into a plastic mint box. In order to be able to build this, we'll have to learn a lot about amplifiers, LC oscillators, mixers, antennas and FM. This project assumes you're already comfortable build your own PCB boards. If you're not please take a look at the homemade pcb's tutorial before you continue. It will help you out a lot.

Here's a Leach Amplifier based on 2SC5200 and 2SA1943 output power transistors that can provide up to 700W of power. The mechanical design is relatively simple, the transistors are placed on the two cooling profiles with a height of 66 mm, width 44mm, overall length 260mm. They are turned against each other Thus, from the cooling tunnel. Coolers are attaching the nylon backing which allows the assembly of transistors without washers, and thus better transfer of heat. DPS amplifier is at the top of the tunnel and the transistors are soldered from the bottom of PCB.

The amplifier design includes not only the final stage of the source (rectifier, filter) and protection against DC voltage output amplifier and speaker connections delayed. As already mentioned, the amplifier is designed as a single-module. This means that on one common board rectifier, filter capacitors, protection And definitely amplifier. Regarding the components of the external solution, the solution based on the original Mr. Marshall Leach. The proposal is adapted for the proposal. in the amplifier are used for temperature sensing diodes are replaced with one sensing transistor mounted on the end of the main condenser and field Tranda. This transistor provides a thermal feedback and thus of a stable quiescent current amplifiers. Privacy speakers are powered directly from the voltage amplifier. As for mechanical design, is probably the most complicated in the whole amplifier. Cooling is done by the Al blocks that are attached to the main cooling profile. ZH6465 profile is used. The terminal transistors to heat is released through Al strips with a thickness of 6 mm in the lateral beams and passing into the cooler. more pictures.

For a long time I needed a good programmer pussy, even if it is programming, so from time to time the application gets where it is used. So I decided to build the programmer. I chose between a couple of projects from different authors, but eventually won PICkit2. Microchip released the schema directly in the user manual for the programmer. On the Internet there are multiple versions of the programmer, it's usually cropped version of the log analyzer features, UART terminal, etc., 12V inverter is a modified version of it and control the MOSFETs, unlike bipolar transistors used in the original design. And it also showed that becomes due to the switching inductance feta leave. Finally, I chose to use the original scheme, although it is quite complicated and the parts used in our country can not normally buy, but my problems with finding parts easily solved. I bought a transistor, the 16F2550 PIC and a few other things, resistors and fry the rest I bought from "us". The price is pretty high, unfortunately, moving it around and 600CZK, the main prize and two processor makes the EEPROM. Below we describe the involvement and put into operation.

After I built several LM3875 and LM3886 gainclone amplifiers, I was totally impressed by their audiophile sound quality. My design goal is to create a audio power amplifier that can deliver 300W into my 4-ohm DIY speaker with low distortion. I want it to produce deep, tight and punchy bass while keeping the excellent mids and highs from my other gainclones. My design uses a PCB to hold 3 paralleled 3886s (i.e. PA150), and then I use the DRV134 to bridge 2 of the PA150 PCB boards. The function of DRV134 is to convert the un-balanced input signal to a balanced signal, so that the non-inverted signal is fed to one PA150, and the inverted signal is fed the another PA150. One of the PA150 is connected to the speaker's positive input, and the other PA150 is connected to the speaker's negative input. Because of this push-pull configuration, the total gain of the amplifier is doubled. Each PA150 has a gain of 20, so the gain of the BPA300 is 40.

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