A Draught Proposal

A Draught Proposal

- Peter Kenington

A step up (or down) Having been caught out by the availability of both 12V and 24V supplies on the same steaming bay and the same connectors, depending upon who was last (or is currently) using the club blower supply, I was determined to use my electronics background to come up with a ‘universal’ solution to this problem. The system was to have the following specification:

1. An ability to cope with a 12V or 24V DC supply without having to know, in advance, which was available or in use.

2. A pre-settable output voltage, which did not change whichever input voltage was being used (eliminating the need to carry around a multimeter to measure either or both of the supply and output voltages).

3. A ‘nice to have’ would be the ability to vary the speed of the blower, to allow it to be adjusted as the fire progressed from the initial lighting of charcoal or wood, through to a fully ignited coal-bed.

Fortunately, modern switched-mode regulators have the ability to meet all three requirements and, even more usefully, are available as ready-built circuit modules for only a few pounds. These are typically in the form of DC-DC converter modules, which provide exactly the functionality we require.

The converter board I chose was based around the XL6009 buck-boost converter chip from XLSEMI (photos 9 and 10). This chip is widely used in DC-DC converters for a range of applications and it is important to choose a board which has both ‘buck’ and ‘boost’ capabilities, since this device can be used for either, individually, or both together and different commercial circuit cards covering all three options are widely available. So - what do these bizarre terms mean?