MPS-U45 Transistors

On Dec 3, 5:14 pm, TVisitor wrote: > I'm trying to gather up some parts for repairing a Gottlieb System

80 > machine. This machine has a 74LS139 which goes through a 7416 > invertor which drives a MPS-U45 transistor as a pre-driver for 2N3055 > transistors that drive a solenoid. >

Yep - crosses to NTE272. It's just a modest NPN Darlington. Should be able to find something at ON Semiconductor. Being a solenoid pre- driver probably doesn't need any speed, just current gain.

If it was OK to _not_ have it, don't you think they would leave it out in the first place?

GG

"TVisitor"

** Yep - the TIP110, 111 or 112 are very similar and also TIP120,121 or 122.

Should be readily available and low cost.

Note: the pin out is different, though both have the collector as the tab.

From the front, it reads: EBC for the MPSU45 and BCE for the TIPs.

** Bad idea.

....... Phil

little

Those old Motorola package transistors such as the MPS-U45 have the unfortunate EBC pinout arrangement whereas the more common modern TO126 case types, for which there are many which would be suitable, uses the ECB pinout.

Firstly the data for your desired MPS-U45

I would suggest a Zetex BCX38C would be a good drop in replacement

(don't be fooled by the small E-line package, they handle heaps of power)

Now, depending upon your location, you may not find Zetex devices all that readily available. I am guessing you might be in the US so to help you locate a US supplier try one of the links here

You could also try Newark

snipped-for-privacy@yahoo.com suggests the NTE272, which is fine, and while it is a direct replacement for the MPS-U45, you might not like the price asked by such suppliers as Jameco who want USD11.80 ea for 25+.

The 2N3055 doesn't have very much current gain on its own.

Graham

================================================================ Seems like a logic level mosfet could replace the MPS and the

2N3055... just need something that turns on at 5V and handles the current.

If you can figure out how to integrate that into your circuit.. :) that's only good for 30 volts Vds how ever, it will do 60 amps continuos, 180 amps pulsed and only requires 4.5 volts at the Vgs to turn at a whooping low 12 mohm. (0.012) ohms. and its 1.39 at mouser or at least it use to be :)

--
"I\'d rather have a bottle in front of me than a frontal lobotomy"
http://webpages.charter.net/jamie_5

or

While a possible solution, a logic level mosfet would introduce other problems. The OP said the power device (2N3055) is several feet from the driver transistor (MPS-U45). The obvious place to install the mosfet would be where the 3055 is currently situated, and since the mounting arrangements of TO3 and TO220 devices are entirely different there is an obvious mechanical problem to be overcome. The next problem to overcome is that driving the gate over the long length of conductor currently between the MPS-U45 and the base of the 3055 would require some noise/spike suppression added to protect the gate of the mosfet. Since the 3055 is doing splendidly as a solenoid driver as is, and there is no shortage of suitable drop-in NPN darlingtons which will do the job of the MPS-U45 at low cost, why change anything? Change for change-sake, or modernity, is not always a wise solution.