ZX Spectrum Transistors
Some of the transistors originally used in the Spectrum are now obsolete - listed below are some suitable replacements.
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A general purpose NPN transistor that can be used to make an alternative version of composite video mod on the Spectrum. Using a transistor instead of a simple wire or capacitor provides a stronger signal, usually giving a brighter picture. It also buffers the Spectrum's video circuitry so much of the load is taken by this transistor. However, it may not be compatible with modern LCD TVs.
Transistor video mod connections:
- Collector (left lead in image) to 5V pad (TV modulator power, disconnect the TV modulator power wire)
- Base (centre lead) to Spectrum video out pad (disconnect the TV modulator signal wire)
- Emitter (right lead) to video socket - it's best to use a small piece of wire to extend this lead.
Please see this article for details.
A cheaper replacement for the obsolete ZTX313 (has same pin-out / case orientation and approx same spec)
- Should be oriented as per the silk screen printing on the PCB.
- As the MPS2369 has a slightly higher gain, if used at TR1/TR2 it can increase the picture brightness - this may create white flaring in the standard RF video output (but this not an issue if the Spectrum is composite modded) . If in doubt, use ZTX313 at TR1/TR2.