What is this - Page 1
Forum section: electronics / beginners

author: AirScooter
author_rank: Contributor
timestamp: March 22, 2021, 01:05:47 pm
content: Can anyone tell me what this is please. It is marked E505 and has a single red dot on its top.

author: retiredfeline
author_rank: Frequent Contributor
timestamp: March 22, 2021, 01:13:32 pm
content: I wish your second picture was sharper and zoomed in on the item. It looks like a transistor, if has 3 terminals. Or maybe a LED if 2 terminals and the top is red.Those are some seriously old ceramic DIPs.

author: SeanB
author_rank: Super Contributor
timestamp: March 22, 2021, 01:23:53 pm
content: Normally hat package was a diode or transistor, led's in this generation did not use the ceramic and epoxy fill package, but used a modified TO18 package with a glass top to allow light out. Very likely a transistor that has had the absolute snot blown out of it, but the case did not shatter. But a better image is needed, especially of where it goes on the board.Looking at the board and the front that screams old Fluke, it probably is a reference diode, likely 6V8, either a simple temperature compensated zener, thus the looking like a capacitor, because there are 2 compensation diodes in the package, or a speciial Fluke zener, which is pretty much the same.

author: xavier60
author_rank: Super Contributor
timestamp: March 22, 2021, 01:30:42 pm
content: It gets a mention here,https://www.eevblog.com/forum/metrology/the-ltflu-(aka-sza263)-reference-zener-diode-circuit/msg1285938/#msg1285938

author: retiredfeline
author_rank: Frequent Contributor
timestamp: March 22, 2021, 01:31:02 pm
content: Quote from: SeanB on March 22, 2021, 01:23:53 pmI was remarking on the DIPs in the sockets.

author: Jwillis
author_rank: Super Contributor
timestamp: March 23, 2021, 09:11:05 am
content: I can't really see it well but I keep getting a reference of the E505 as a 1ma JFET current regulator .

author: Gyro
author_rank: Super Contributor
timestamp: March 23, 2021, 10:57:33 am
content: Quote from: Jwillis on March 23, 2021, 09:11:05 amAgreed. I just pulled out my 1979 Siliconix Plastic FET databook - The TO92 equivalent, the J505, is a 1mA current regulator diode (JFET type). Replacement is available from Linear Systems...https://shop.micross.com/pdf/LSM_J505_TO-92.pdfP.S. It probably wouldn't be recognised correctly on a cheap transistor tester.

author: tszaboo
author_rank: Super Contributor
timestamp: March 23, 2021, 11:08:11 am
content: I think that is two blurry images.

author: Shock
author_rank: Super Contributor
timestamp: March 23, 2021, 12:11:36 pm
content: It's a... have you checked the Fluke 8000A schematic and parts list?

author: Psi
author_rank: Super Contributor
timestamp: March 23, 2021, 12:17:22 pm
content: Quote from: AirScooter on March 22, 2021, 01:05:47 pmThat's not a component, that's a spider.

author: cheater
author_rank: Regular Contributor
timestamp: March 23, 2021, 03:43:13 pm
content: This could well be a reference diode used as a voltage reference for the DMM to compare other voltages against (and essentially all other measurements). If you replace it you'll have to recalibrate your meter.