The Digital Model Train Part 8

THE DIGITAL MODEL TRAIN PART 8 Construction & testing IC sockets may be used, but it should be noted that this is no longer accepted prac- tice, at least as far as standard logics cir- cuits are concerned. Some sockets are more expensive than the IC itself and, more importantly, the reliability of a circuit is inversely proportional to the number of connexion s. None the less, for the more expensive ICs, such as the A-D converter (IC25) and the EPROM (IC13), a good- quality socket is recommended. Bear in mind also that the printed-circuit board is through-plated: any desoldering of ICs is, therefore, a tricky operation. So, check and double-check whether the IC is the correct one before soldering it on to the board. The parts list shows ICs of the HC- and HCT-type. The HC-types may be replaced by HCT-types, but HCT-types should NOT be replaced by HC-types. Power supply. Start by fitting D38-D41, D36, C24, C25 and C27. Next, fit IC29 on to the relevant heat sink and mount the re-...