5V Trigger for 12V Relay

pilot makes the setup all i used is the pressure switch and i can use it to trigger -or+ doesnt matter to me send power by +trigger to relay or send power by switching ground on relay im ok with wiring just not sure about npn transistors or how they work i found a prouduct from (pie) called cyclops that in basic basic form is a relay that will switch with very low ac or dc or audio nice stuff but kind of bulky

if i could up the amps comming out of the switch (66ma) to (140ma) i could use a spst 12v relay on this setup     what type of transistor specs ect would i be looking for and will it increase volts and amp

thanks again

sorry about the pic not to good wit posting

thanks

I would just get a 5vdc reed relay.  The contacts won't switch quite as much, but they will switch 12vdc.  Reed relays use extremely low current and you can get them with 5vdc coils.