North Adelaide
Could a bd681 transistor be used instead of a cen-u45 if the 2 legs (2,3) on the bd681 were twisted around
Ralph
(Topic ID: 189853)
Ray Twp., MI
Cant buy them in Australia , found them at future electronics at $1.28, but $70 for shipping is bit high in price. Marco specialities sells them for around $5.95 each. Criush what site online did you buy them from if you could put the link up that would be great.
I used to sell U45 transistors made by Central Semiconductor ... then Central Semi signed an agreement with Mouser. Shortly afterwards, Central Semi told me they were no longer interested in my business and that I had to buy their parts from Mouser. Like hell...
The BD681 has a much higher VCE saturation voltage - by about 1V (resulting in dimmer lamps).
The BD681 has a different pinout. Would need to cross two legs.
And the BD681 has nowhere near the gain that the U45's had. At nearly same load, BD681 current gain has a minimum of 750 where the U45 has a min gain of 4K. At the same load - even the TIP102 is a better choice than the BD681 (but still has wrong pinout). The gain makes a big difference considering this transistor is being driven directly from the output of a 74175 (or 74LS175). If you were driving two true lamps such as #44s then I would stick with the U45. Can probably get by with the BD681 if driving LEDs.
Reply
Wanna join the discussion? Please sign in to reply to this topic.
Hey there! Welcome to Pinside!
Donate to PinsideGreat to see you're enjoying Pinside! Did you know Pinside is able to run without any 3rd-party banners or ads, thanks to the support from our visitors? Please consider a donation to Pinside and get anext to your username to show for it! Or better yet, subscribe to Pinside+!
