hi, i hope this is off topic enough ,as it is not a question. anyway it all started many moons ago, when old mate give me a beginners electronics book. i knew the basic ohms law, as i have been off grid power for 27 years now. so i tried to make a transistor work. so after lots of tries/ failures, i swore and cursed and gave the bloody book back. fast forward to 5 days ago, i decided a transistor would solve my problem .
so get on www and try and learn again, [i am proficient with metal and wood though], i still had a couple of bd139,s from way back ,so give it another go. i sort of got one to work, but the relays stayed latched on , after i turned base off!...? . ok try the other one, FAIL !. during these tests i destroyed the MA function on 2 dmms.
so, off to jaycar , [electric/onics retailer] for $10 dmm and 4 [bc338] and 4 [pn2222a] transistors]. at home i double check data sheet and EPs guide/equations [pn2222]. all good, connect c/e to load [40MA relay coil] and on it goes !..what the *%&#. the base was not connected yet . so i triple check data sheet , equations and wire connections again. try again , same thing , this is really starting to do my head in , [doubting my sanity] , flash backs to my first attempts etc. i was at a loss and ready to kill anything with a transistor in it.
arghh, then the "penny dropped" , to check numbers on transistor, so,i had to find a microscope [nearly] to read the numbers [p2n2222a], back to google ,123=CBE whereas [pn2222a is 123= EBC] . they are one and the same. i specifically asked for [pn2222].... what is it,? about engineers ,that they have to complicate everything..the moral about this story is, rule #1 never trust a salesman. rule #2 [see rule #1] sorry about the rant , and i will ask my questions in the appropriate forum...
regards..
dennis..
so get on www and try and learn again, [i am proficient with metal and wood though], i still had a couple of bd139,s from way back ,so give it another go. i sort of got one to work, but the relays stayed latched on , after i turned base off!...? . ok try the other one, FAIL !. during these tests i destroyed the MA function on 2 dmms.
so, off to jaycar , [electric/onics retailer] for $10 dmm and 4 [bc338] and 4 [pn2222a] transistors]. at home i double check data sheet and EPs guide/equations [pn2222]. all good, connect c/e to load [40MA relay coil] and on it goes !..what the *%&#. the base was not connected yet . so i triple check data sheet , equations and wire connections again. try again , same thing , this is really starting to do my head in , [doubting my sanity] , flash backs to my first attempts etc. i was at a loss and ready to kill anything with a transistor in it.
arghh, then the "penny dropped" , to check numbers on transistor, so,i had to find a microscope [nearly] to read the numbers [p2n2222a], back to google ,123=CBE whereas [pn2222a is 123= EBC] . they are one and the same. i specifically asked for [pn2222].... what is it,? about engineers ,that they have to complicate everything..the moral about this story is, rule #1 never trust a salesman. rule #2 [see rule #1] sorry about the rant , and i will ask my questions in the appropriate forum...
regards..
dennis..
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