Brightspark Magnetos

The 'Universal' EasyCap

Overview

The 'Universal' EasyCap is an ignition condenser suitable for use not only in all types of magneto (rotating-coil, rotating-magnet and flywheel), but also in battery-coil ('Kettering') ignition systems. It is designed so that it can be shaped to fit wherever the space permits. In view of its high-tech ceramic capacitor, the Universal can be expected to last far longer than the humidity-affected paper condensers that have traditionally been used in recent decades.

The 'universal' EasyCap consists of a 1.8" square of FR4 (glass-reinforced epoxy) circuit board, clad with tinned copper on both faces, and with its high spec. capacitor soldered to the top of the circuit board adjacent one edge. The outer terminal of the capacitor is connected through the board to the bottom layer of copper. The inner terminal of the capacitor is connected to the top layer of copper outside the little green rectangle.

Versions are available as standard with a capacitance of 150 nF (0.15 µF) and 220 nF (0.22 µF). Other values can be made to special order at a premium. The capacitors are rated at 630 V dc, and the universal EasyCap has an operating temperature range of -55 to 125 °C. If you do not know which capacitance is required for a particular application, a rule of thumb seems to be to use 150 nF for rotating-coil magnetos, and to use 220 nF for rotating-magnet and flywheel magnetos, and for battery-coil systems.

The board can be sawn, ground and/or sanded to any desired shape. The bottom of the board is marked with a grid to assist in laying out. The board can be drilled to receive one or more screws which can serve to mount the EasyCap and/or make electrical connections to the copper layers. In many applications, the universal EasyCap can be used to replace an existing insulating plate or washer under the head of fixing screw in the contact-breaker assembly so that the EasyCap is not only held in place, but the electrical connections are made automatically. Wire can be soldered to either of the copper layers, but in most applications this will not be necessary.

The area occupied by the capacitor is extremely small, so that the capacitor can be tucked away in a very small space. The area of the board is relatively large to give the maximum flexibility in designing a condenser for any specific use. In most cases, the vast majority of the board will be cut away and discarded.

Tips

Plan the required shape of the board carefully. Even if you are using a drawing from the examples below, make a mock-up out of card or other suitable material and check that it fits. If the EasyCap will be located near an adjustable component such as an adjustable contact breaker point, check that the required range of adjustment is still available.

Chamfer the edges of the board where necessary to avoid inadvertent contact between the edge of a copper layer and something that it shouldn't touch. Lightly countersink any screw holes where necessary to avoid inadvertent contact between the screw and the edge of a copper layer around the hole.

If the bottom face of the universal EasyCap needs to make electrical contact with whatever it is fixed to, remove the printed grid with very fine abrasive paper.

A junior hacksaw is good for sawing the board. A bench grinder or Dremel^® type grinder is useful. The dust can be irritating. Use a face mask and, of course, eye protection. If clamping in the vice, use rags to protect the board. Do not clamp the capacitor.

click on picture to enlarge

Examples

In this section, we're putting together some examples of how the Universal EasyCap can be used. Obviously the more examples, the better. So, if you design another application for a Universal EasyCap and would like to share with others, please email us details including photos and dimensioned sketches to CU.apps@brightsparkmagnetos.com. For each example that we publish, we'll be happy to send the submitter a sample Universal EasyCap with our compliments.