XPost: sci.electronics.basics, sci.electronics.components, sci.e
ectronics.design
XPost: sci.electronics.repair
From: pcdhSpamMeSenseless@electrooptical.net
On 09/17/2015 08:05 PM, krw wrote:
> On Thu, 17 Sep 2015 20:16:17 +0100, "Ian Field"
> wrote:
>
>>
>> "DaveC" wrote in message
>> news:0001HW.1B9BFB3100248A5811E4F83CF@news.eternal-september.org...
>>>> How's it measure?
>>>>
>>>> (Or if it's dead, is there another one probably working that you can
>>>> test?)
>>>>
>>>> Tim
>>>
>>> Dead. Other with identical markings measure as NPN. What else to determine
>>> from measurements?
>>
>> You can usually distinguish the B/E junction because it will zener somewhere
>> around 5 - 8V ish.
>>
>> You need to keep the test current pretty low - you can get ultra-efficient
>> LEDs that give a useable indication at only 2mA. Hook one of those up with
>> an A23 12V keyfob battery and a current limiting resistor.
>
> InGaN (true) green LEDs are quite bright at only 1mA. They can be
> seen at much less than that.
>
An ordinary 4-3/4 digit DVM on the lowest volts range (400 mV usually)
makes a poor man's picoammeter. The 10 megohm ones read 1 LSB (0.01 mV)
for 1 pA. Some of the older ones, where the lowest range doesn't have
the 10M resistor in parallel, can be much more sensitive than that.
You aren't going to hurt a transistor with a nanoamp of reverse base
current, and the measurement is pretty simple.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203
Briarcliff Manor NY 10510
hobbs at electrooptical dot net
http://electrooptical.net
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
|
