At risk of teaching how to suck eggs: It's normal to pull something like a solenoid down to ground using an N-channel MOSFET. For logic level gate drive the MOSFET neets to be a logic-level device - something everyday like an IRF-540 won't completely turn on at 5V - you need an IRL- version. I guess in your case it's in a package, and hopefully as such it is logic level!
In order to avoid a negative voltage spike from the inductive solenoid, a diode should be reverse-connected across the solenoid. If that wasn't done your MOSFET will be fried. Otherwise, you don't need to have a diode in series, only if you have to guard against reverse connection of your 24 V. Maybe the 24 V is AC? In which case there should be no diodes and the switch is a triac, generally driven by a trigger device, normally an optocoupler. hth Kevin. On Thu, 2011-02-17 at 13:36 +0800, James wrote: > Hi > > My kingdom to anyone who can id the parts U15 and U16 > > They are marked '44108' 'SA1<delta>' 'W97k' > http://tigger.ws/downloads/img_1329.jpg > > Why this is not wildly OT: > I'm making these POS (Micros 2010) run linux. > The CashDraw solonoid takes a diode to +V, the IC to somewhere to control it > and a connector to the cash drawer solonoid > > I think they are transistors, or OC logic gates (high voltage since the > drawer > is 24V) but I cannot find anything useful. > > Thanks > James -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
