Brian Parker

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Have tried to paste sketch of the above, failed twice! How do you paste/insert without going through the gallery?

Last sentence should read All available from Maplins or RS.

Nicads are robust but not bullet proof. They should be fully discharged before charging at rates above C, but if cells in a series nicad are discharged to below one volt at a higher discharge rate than C/5 there is a danger of a cell becoming reverse charged due to its low internal resistance. Not good for the cell!! (If necessary fully discharge with a suitable bulb). The maximum charge rate for indefinite charging is C/8. The battery is fully charged when 150% has been returned, i.e. around 12 hours. A constant current charger must  be used for indefinite charging. The current remaining consant throughout the time the battery is charging/connected (use an ammeter in the circuit). High charge rates of up to 10C are permissible (check battery spec.), providing the charge period is controlled as appropriate. A constant current charger is recommended over a constant voltage unit. DO NOT subject a nicad to indefinite charging at a high rate unless the current is reduced to the continuous rate for the battery once charged.  A simple 'home brew' continuous current charger can be built for a few pence using a 3 leg voltage regulator from the L78/TS78 range plus a suitable resister on the output leg, 82 ohm will give 66mA, 22 ohm for 250 mA, 10 ohm for 500mA etc. Use 5W resister for 22 and 10 ohm. Connect a diode across the input and output legs. Link the centre leg (common) to the battery side of the resister. A tantaium capacitor from 'common' to input leg and that's all. You will of course need a suitable power supply/source(PSU) at 12-15 volts. DO NOT connect the PSUground/negative to the L78 'common' but to battery only. Mount the L78 on a heat sink, the resisters will also get a little warm. Don't forget the ammeter. All available for Maplins or RS.

Nicads in parallel can have problems with reverse charging in service due to their low internal resistance.

Bristol Beaufighter Westland Lysander  Hawker Sea Fury

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My vote would be for..        i)  Bristol Beaufighter       ii) Lysander      ii) Sea Fury

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My three votes are.. 1. Avro 504 2. Stuka 3. Islander