CGA-SCART adaptor

The adaptor has the great advantages of not needing a separate power supply and requiring so few external components that these can easily be accommodated in the SCART connector. The signals on the R, G, and B pins of the CGA card are converted from TTL level to SCAM’ level with the aid of transistors[…]

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Low power NBFM transmitter

The transmitter is a crystal-con-12 trolled, battery-powered, one-chip narrowband frequency modulation v(NBFM) model for operation in the 27- m band, primarily as a wireless microphone*. The circuit is an application of Motorola’s MC2833 single-chip VHF narrowband FM transmitter IC, designed to work in the 27-MHz band. The transmitter output power is about 10 mW (+10[…]

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Single-chip mains supply

Single-chip mains supply: Harris’s Type HV-2405E IC, connected with a few external components as shown in the diagram, enables the direct derivation of a regulated 5-24 V d.c. supply from a 100-260 V a.c. mains supply. The peak output current of the device is 500 mA. The chip contains a pre-regulator that arranges the charging[…]

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Power-on delay for Atari ST

Power-on delay for Atari ST: When the Atari ST is provided with an external hard-disk drive, it has to be reset after about 15 seconds, as otherwise the drive is not enabled. The delay circuit presented here obviates that inconvenience by ensuring that the computer is not switched on until a (presettable) period of time[…]

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