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The Shop => Electronics & IC Programing => Topic started by: johnstij on November 20, 2010, 05:28:58 PM

Title: BC848 NPN transistor equivalent
Post by: johnstij on November 20, 2010, 05:28:58 PM

Hi. Can any one suggest an alternative/equivalent to a BC848 NPN transistor.
Thanks . Ian

Title: Re: BC848 NPN transistor equivalent
Post by: John Swift on November 20, 2010, 06:34:25 PM

Hi Ian ,

the transistor is basically a surface mount version of the BC108
if the pcb design makes it possible ,you could try a TO92 plastic NPN transistor like a BC547 or BC548 (can try maplin for this)

otherwise try ebay , RS components or farnell for a BC848

what is the transistor used in ,and how many do you need  ?
I may have one or two SMT transistors that may work

              John

Title: Re: BC848 NPN transistor equivalent
Post by: picclock on November 21, 2010, 04:31:39 AM

Hi johnstij

I have some, BC848B. The B suffix is for hfe range, so if yours lacks the suffix they will be perfect. How many do you need ?

picclock

Title: Re: BC848 NPN transistor equivalent
Post by: johnstij on November 21, 2010, 06:58:42 AM

Hi.
Thanks for the replies.
I'm trying to control the speed of my CNC mill spindle. It runs on Mach 3 software. The circuit i found on the Mach 3 forum converts a PWM signal to analogue 0-10v DC which goes to the motor VFD.Not sure why the circuit specifies a BC848 as he uses a TO92 case transistor built on vero strip board (as I plan to)
This link takes you to the document, the circuit is on page 11,
 http://www.cjh.com.au//PWM%20Spindle%20Control%20using%20Mach3.pdf
A copy of the circuit is attached.
Thanks  Ian

Title: Re: BC848 NPN transistor equivalent
Post by: johnstij on November 21, 2010, 08:26:28 AM

Hi.
Just looked through my small box of transistors and found a BC107 & 107B do you think either of these are suitable.
Thanks Ian

Title: Re: BC848 NPN transistor equivalent
Post by: John Swift on November 21, 2010, 09:07:44 AM

Hi Ian ,

I would expect the BC107 or BC107B  to be OK

in fact almost any low power silicon npn transistor is likely to work

take a look at the " universal npn transistors "  used by Elektor magazine in their simple projects

 search for   " TUN TUP DUS DUN "

      John

Title: Re: BC848 NPN transistor equivalent
Post by: trevoratxtal on November 22, 2010, 05:00:18 AM

Hello John
the following links may be useful for future lookup
http://www.datasheetcatalog.com/datasheets_pdf/B/C/8/4/BC848.shtml
many other data sheets available here.
Also
http://talkingelectronics.com/projects/TransistorData/TransistorData-P1.html
Cover a large range, if you are looking for a Japanese transistor starting C****
then add 2S in fron making 2SC****
When choosing a substitute try to match or better the characteristics.
If it is for very high frequency( 10meg hertz plus) work then some times only a correct replacement will work satisfactory, but this is rare.
I am sure other folk may have other opinions, but I have found this approach works for me.
Trev

Title: Re: BC848 NPN transistor equivalent
Post by: John Swift on November 22, 2010, 06:04:42 AM

Hi Trev ,

thanks for the info
two usefull links

while a search for data for a transistor very often links to datasheetcataloge.com 

the talking electronics page is one i've missed

the link to philips and the smd marking data I've just downloaded
until now I had no idea what a  2BJ transistor was
my DCA55 component analyser is good , but it does not give part numbers!!!    (its a BC849b by the way)

yes you are right , japanese transistor numbers only make sence if you know they don't print the 2S prefix
on the part


     John