It is basically a variant of the usual magnetic loop, using a toroid balun to get a reasonable match on the three bands.
http://www.g3ycc.karoo.net/rock.htm
This is an example of a power supply to power anything requiring 5 volts DC. This circuit takes low voltage AC in (9-16V AC).
http://www.mrollins.com/pwrsp3.html
Although there already exist many websites about such stuff, another simple DC-DC converter is described here. The output voltage equals twice the input voltage minus the voltage drop across the diodes.
http://df2ck.de/tech/dcdc/
powered by a 9 volt battery.
http://www.mrollins.com/flash4.html
Butterworth filters, Chebychev filters, Bessel filters, Elliptic filters, State-variable filters, Switched-capacitor filters etc.
http://www.maxim-ic.com/appnotes.cfm/appnote_number/733/ln/en
Schematic for a HV High Current voltage doubler. Uses MOT's.
http://www.kwarc.org/bulletin/99-04/tech_corner.htm
http://www.techlearner.com/Semiconductors.htm
A tiny homemade QRP antenna tuning unit - ATU or transmatch - is inexpensive to build and is easily customized for special needs.
http://69.5.23.180/ars/pages/back_issues/2001_text/0401_text/tuner.html
transmitting antenna tuned for 89 MHz.
http://www.solorb.com/gfc/elect/microfm/jpole.gif
designed for 89MHz FM frequency.
http://www.solorb.com/elect/microfm/jpole.gif