A thyristor is *a four-layer semiconductor device* (that is, it is
explicitly not a diode or transistor) consisting of alternating P-type and
N-type materials (PNPN). A thyristor usually has three electrodes: an
anode, a cathode and a gate, also known as a control electrode. The most
common type of thyristor is the silicon-controlled rectifier (SCR).

Off the top of my head... the NSW "C" and "T" suburban sets use chopper
control systems and also the 85 class electric locos and the SLR Variotrams In
VIC the Z3, A, B and W8 trams and some Comeng suburban cars also use
chopper control.

I'm sure others may know of further examples.

On Saturday 16 March 2024 at 03:06:43 UTC+11 Mick Duncan wrote:

> Gday All

>

> Between series parallel K,camshaft and unit remote control and VVVF of

> today, there is Chopper control.

>

> Some questions.Were there some Chopper controls with series,parallel

> as the dwgs Ive seen have all the motors in series

>

> Is the Thyristor a diode with a base that can have its resistance

> changed by a 3rd wire input so it can conduct or not

>

> What Oz trams and Sparks had Chopper control

>

> Cheers, Mick

>

>

>