What is this capacitor of this FM receiver? - Page 1
Forum section: electronics / beginners

author: AngraMelo
author_rank: Regular Contributor
timestamp: August 24, 2021, 02:23:04 am
content: Hey guys,Im trying to build this FM receiver and it's requested a 0.001 capacitor.All other values are given but this one.Is this a 1nf?Also, if anyone is interested this is where the circuit came from:

author: xrunner
author_rank: Super Contributor
timestamp: August 24, 2021, 02:28:36 am
content: Quote from: AngraMelo on August 24, 2021, 02:23:04 amI would say yes.

author: David Hess
author_rank: Super Contributor
timestamp: August 24, 2021, 02:32:51 am
content: Both capacitors marked 0.001 are 0.001 microfarads or 1 nanofarad or 1000 picofarads. Decoupling capacitor C2 hold the AC impedance low and C3 bypasses RF around VR2.

author: fourfathom
author_rank: Super Contributor
timestamp: August 24, 2021, 02:53:21 am
content: I have to say that I'm a bit concerned about that "VR1" 10K regeneration control potentiometer. When it's turned all the way down it is essentially shorting out the battery. Perhaps it could be re-wired, with the battery connected to the top of the pot, and R1 connected to the wiper?

author: TimFox
author_rank: Super Contributor
timestamp: August 24, 2021, 02:56:37 am
content: Back in the day, the default for non-polarized capacitors was<1.0 is in uF>1.0 is in pFPolarized capacitors in uFunless otherwise specified.

author: AngraMelo
author_rank: Regular Contributor
timestamp: August 24, 2021, 03:33:28 am
content: Quote from: fourfathom on August 24, 2021, 02:53:21 amThank you for that, Ill pay attention to it!

author: AngraMelo
author_rank: Regular Contributor
timestamp: August 24, 2021, 03:35:39 am
content: Quote from: TimFox on August 24, 2021, 02:56:37 amI did not know that, I have a bunch of books with old circuit diagrams that will make much more sense now!

author: bdunham7
author_rank: Super Contributor
timestamp: August 24, 2021, 04:58:33 am
content: Quote from: TimFox on August 24, 2021, 02:56:37 amBackWay backin the day, the default for non-polarized capacitors was<1.0 is in uF>1.0 is inpFuuFPolarized capacitors in uFunless otherwise specifiedsuch as in millimicrofarads (mmF)

author: TimFox
author_rank: Super Contributor
timestamp: August 24, 2021, 01:02:37 pm
content: mmf = micro micro farads (mickey-mikes) back then, and mfd = microfarad

author: bdunham7
author_rank: Super Contributor
timestamp: August 24, 2021, 07:36:29 pm
content: I just saw a manual or something the other day with millimicrofarads shown as mmF on the diagram--all spelled out, no error, they meant nanofarads. It was ancillary to whatever I was doing so I can't remember which one it was right now, but I thought it was pretty funny. If I find it I'll post it.

author: TimFox
author_rank: Super Contributor
timestamp: August 24, 2021, 08:29:18 pm
content: Another anomalous usage: I have a pre-war Simpson 260 (wherein the dry cells for resistance were soldered to cloth-insulated wires) that uses majuscule “M” to indicate 1000 (on the ohms scales), meaning the Roman numeral. At age 12 or so I saw a capacitor in a schematic labeled in “mfd” and assumed it to be an abbreviation for “modified”. Life is more consistent now, but I wish the standardizers had settled on “u” for micro, as Spice did, to avoid a common “special character” in frequent usage.

author: David Hess
author_rank: Super Contributor
timestamp: August 24, 2021, 08:38:56 pm
content: I have also seen uuF for picofarads.

author: TimFox
author_rank: Super Contributor
timestamp: August 24, 2021, 09:28:53 pm
content: Yes. I remember when pF became popular in US, later joined by nF.For a while, there was competition between BeV (Brookhaven electron volts) and GeV (Geneva electron volts) in particle physics.It was only after 1974 that the UK adopted the US definition of “billion” (thousand million) over the previous British definition (million million).This all makes reading historical technical literature more interesting.

author: Bassman59
author_rank: Super Contributor
timestamp: August 24, 2021, 09:52:54 pm
content: Quote from: bdunham7 on August 24, 2021, 07:36:29 pmThis kinda shit is why the US still doesn't use the metric system!

author: TimFox
author_rank: Super Contributor
timestamp: August 25, 2021, 02:51:12 am
content: The United States went officially metric in 1959--they just didn't tell anyone.

author: gbaddeley
author_rank: Regular Contributor
timestamp: August 25, 2021, 03:28:15 am
content: This is not an issue with the metric system. The abbreviated terms for 10^n values of capacitance in Farads has changed over the years. It mearly requires an understanding of what they mean, and the context in schematics and markings on parts.A unit of capacitance was Jars in the late 19th century. You can guess what it relates to…

author: mikerj
author_rank: Super Contributor
timestamp: August 27, 2021, 01:32:07 pm
content: Whoever designed that regen control must have missed their morning coffee, unless it was intended to serve double duty as a regen control and "battery eliminator"