Composite circuit protection devices

An electrical circuit comprising

• (1) a power source;
• (2) an electrical load;
• and
• (3) a circuit protection device which is in series with the load and which comprises
• (a) a first laminar substrate which is electrically insulating and a second laminar substrate, each of said substrates comprising a first laminar surface and a second laminar surface;
• (b) a first electrical component which is physically adjacent to the first laminar surface of the first laminar substrate and is mounted directly thereto, said first component comprising (i) a laminar PTC element composed of a conductive polymer which exhibits PTC behavior with a switching temperature Ts, and (ii) at least two laminar electrodes which can be connected to source of electrical power so that current passes between the electrodes through the PTC element;
• (c) a plurality of second electrical components, one of which (i) is physically adjacent to the first laminar surface of the first laminar substrate, (ii) is in good thermal contact with the first component, and (iii) is electrically connected in series with the first component;
• and
• (d) an electrical lead which electrically connects the first and second components,
• said circuit having a normal operating condition in which the PTC conductive polymer composition of the circuit protection device is in its low temperature, low resistivity state.