This is a ery simple serial ISP progammer for AVR microprocessors. The schema can be found here. It is Sample Electronic Programmer compatibile and can be used with Bascom, WinAVR etc.
Previously I used programmer with only 330 ohm resistors in series with MOSI, RESET and SCK. It worked quite good, but in new version I used buffers to improve separation between LTP and AVR. In plans full galvanic isolation using optocouplers.