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Old 23rd Feb 2021, 4:01 pm   #9
GW4FRX's Avatar
Join Date: Aug 2005
Location: Shrewsbury, Shropshire, UK.
Posts: 149
Default Re: Plastic or ceramic ICs?

>4049A - the A series were the originals, the B series came later and it appears had a higher voltage rating, plus came in B (buffered) or UB (unbuffered). The idea of the buffered one was they had an output buffer which meant the output high/low resistance was independent of logic state of the inputs; the penalty was they were slower.<

Ah, that's interesting. I noticed that in my particular application (a control unit for a VHF linear amplifier) the 14049A is noticeably slower to switch as the HV sample comes up than an HEF4049B and wondered whether it was a buffer issue.

>The 4049A by the way was a hex inverter. If you need I can copy the datasheet for you.<

That's very kind but I do have an original Philips LOCMOS data book and a few other useful items. It was amusing to see from a contemporary STC components catalogue that ordinary plastic HEF4049s were 4.60 each in 1985 whereas posh mil-spec ceramic ones nowadays cost about a quarter of that!
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