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THE AM BULLETIN BOARD => Technical Forum => Topic started by: WA2SQQ on January 14, 2020, 09:50:31 AM



Title: Need assistance ID'ing a capacitor
Post by: WA2SQQ on January 14, 2020, 09:50:31 AM
Not directly AM related, but I need a quick answer to a component identification situation. Im at the office and dont feel like waiting till I get home to measure this. This USB dongle has 3 caps in parallel, labeled 1201J I know the J is 5% tolerance. Caps usually have a 3 digit code, but this one appears to be 4. Anyone know about 4 digit cap codes?

Interesting circuit, from a device marketed to high end audio people a USB line conditioner. Ground (pin 4) is separated from USB shell part of the connector. Simple RC network comprised of the 3 caps in series with a 33 ohm resistor between the shell and ground. Possibly it might improve a ground loop situation but hardly what customers who purchased it claim it does. Anyone want to guess what this sells for? $299 No joke!


Title: Re: Need assistance ID'ing a capacitor
Post by: N4LTA on January 14, 2020, 11:07:59 AM
I'd guess 1200pF but I might be wrong. 1201 on a SMD resistor usually means 1200 ohms - usually...

Pat
N4LTA


Title: Re: Need assistance ID'ing a capacitor
Post by: K1JJ on January 14, 2020, 12:00:11 PM
I had a box of silver micas that were marked 39J, 202J, etc.  They were all picofarad, meaning 39 pF, 202 Pf....

So in your case this could mean 1200 pF =  the more common .0012 uF.

Just a guess though.

T



Title: Re: Need assistance ID'ing a capacitor
Post by: KD6VXI on January 14, 2020, 12:07:42 PM
http://m.diytechstudio.com/apps/4-digit-capacitor-value/4-digit-capacitor-value-finder

--Shane
KD6VXI
AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands