On Saturday 19 February 2011 09:00:04 slug-requ...@slug.org.au wrote: > 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. > > 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.
Alas I get to keep my kingdom. but thanks to Nick and to Kevin for research and suggestions. Tracing out the circuit shows that the mysterious part must switch to ground in response to a logic signal, so I'll walk past and not be stumped James -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
