An UJT has a resistive path that becomes much more conductive when triggered, while the SCR has a reverse junction that conducts when triggered. Also, the SCR stays on after the gate voltage is removed until the A-K current drops to a critical level, while the UJT turns off when the emitter current is removed. So, they are not exactly a direct replacement, although I admit that in some specific applications there may be some sort of adaptation possible. Cheers, Isaac Em 30/08/2016 15:50, graham foulkes escreveu: > Hi > A UJT, can definitely be emulated by a SCR, or better still an SCS. The > unique characteristics of the UJT can be found in the very useful, ancie= nt > (like me), GE transistor manual. Unlike the aforementioned 10F's and cort= ex > offerings, UJTs only need a minimum of 3 resistors and one capacitor plus= a > smidgen of math to calculate the pulse rate, work with a wide range of > supply voltage and..... can deliver a heck of a sight more current in th= at > tiny little spike, perfect for triggering circuits, ramp generators, clam= ps > etc....... > Pics are great, used them from the early nineties, but properly > chosen, versatile analog components still can outperform the digital > implementation of a wide range of functions. Analog world remember, until > you get down to quantum levels. > > On Aug 30, 2016 10:01 AM, wrote: > >> A UJT is sort of like an SCR. It is a sort of triggered diode. >> This isn't exactly correct, but in general, it will give an idea of >> it's purpose. >> >> Regards, >> >> Jim >> >>> -------- Original Message -------- >>> Subject: Re: [EE] UJT >>> From: William Bross >>> Date: Tue, August 30, 2016 8:41 am >>> To: "Microcontroller discussion list - Public." >>> >>> >>> Dave, >>> >>> Slim pickn's is right, and fairly on the pricey side too. >>> >>> >>> >>> >>> >>> I've only used UJTs and PUTs for timers and oscillators that gave that >>> sharp little glitchy type output. So.....maybe a 10F? Would definitely >>> be cheaper nowadays. >>> >>> Bill >>> >>> >>> On 8/30/2016 9:05 AM, Dave Lagzdin wrote: >>>> One still sees schematics posted with UJTs as solutions to things. >>>> I'm curious if anyone has done something with one in recent history an= d >>>> where would you procure such mythical devices? >>>> >>>> Pickn's seem slim at Digikey and Mouser... >>>> >>>> D >>> -- >>> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive >>> View/change your membership options at >>> http://mailman.mit.edu/mailman/listinfo/piclist >> -- >> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist >> --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .