- ME/MA UK 1970's transistors? - 5 Updates
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| frank@invalid.org: Nov 22 10:26PM > but one of them shows a bit more than 1V drop on both BE and BC junctions > (it's NPN). Can I assume this one must be bad? > Any other hint and information is welcome. I removed the suspicious one and put in my curve tracer. Indeed it shows excessive VCEsat at already 5-10mA, I compared the curve to a bunch of random BC147/8 that I had around (same era, should be very similar). The BCs have almost straight saturation line, while this particular ME4101 start to sag towards 0.5V and more already at the 5mA level of Ic. I'm sure it's marginal even for a 1970's transistor. I didn't remove another ME4101 but bought a bunch of them (advertised as NOS), so I'll have fun with the curve tracer once they arrive. Frank |
| Look165 <look165@numericable.fr>: Nov 22 11:33PM +0100 With such aVBE, they surely are Ge transistors, not Si. |
| frank@invalid.org: Nov 23 08:28AM > With such aVBE, they surely are Ge transistors, not Si. They are all Si transistors. Ge have Vbe around 0.3 to 0.4V, I have quite a few devices with Ge transistors. Frank |
| tabbypurr@gmail.com: Nov 23 01:24AM -0800 > They are all Si transistors. Ge have Vbe around 0.3 to 0.4V, I have quite > a few devices with Ge transistors. > Frank I can't imagine what Si tr would have 0.8v V_be or why. Do you know? Geraniums start much lower of course, but also rise higher quickly as current increases. 0.8v on a Ge junction is no cause for surprise. The ME tr you mentioned is a Si device, so I'm puzzled by its V_be. NT |
| frank@invalid.org: Nov 23 01:55PM > I can't imagine what Si tr would have 0.8v V_be or why. Do you know? a faulty/degraded one, that's why I decided to substitute this one. The other have all less than 0.8V VBE, my first measure was actually not correct. Only one measure > 0.8V and I also verified that it has an incorrect behaviour with the curve tracer. > Geraniums start much lower of course, but also rise higher quickly as > current increases. 0.8v on a Ge junction is no cause for surprise. > The ME tr you mentioned is a Si device, so I'm puzzled by its V_be. degraded junctions maybe, degraded material, doping migration, who knows. I have a few samples of "interesting" semiconductor faults, this one is definitely one of them. Another notable one I've found years ago is a 2W zener diode showing 0.7V zener voltage and 0.2V forward voltage. Both ways with very soft knees, it was about to short probably. Interestingly, it was new, never soldered in. Frank |
| paulyuen777@gmail.com: Nov 22 11:10PM -0800 On Friday, July 5, 2013 at 12:30:28 PM UTC-7, root wrote: |
| John Robertson <spam@flippers.com>: Nov 22 08:44AM -0800 On 2018/11/22 7:01 AM, Pat wrote: > the proper frequencies and may or may not interfere with legal > devices. Some even cheat and place a sticker claiming FCC approval. > Buyer beware. Very true with Amazon and eBay 'products'. Brick and mortar businesses are much less likely to sell you junk that interferes or is potentially dangerous... John :-#)# -- (Please post followups or tech inquiries to the USENET newsgroup) John's Jukes Ltd. MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3 (604)872-5757 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out." |
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