Thirdwit strike again: whit3rd wrote: ============================ https://usa.banggood.com/-30-0-30A-Galvanometer-Scientific-Current-Sensor-Sensitive-Ammeter-Electric-Current-Detector-Analog-Display-p-1441415.html> > A moving-needle meter for 30 uA with 100 ohms internal resistance** Such movement have around 3000 ohm R. > can cover the 3mV range, with 30 uV easily resolved. ** Horse poo. The meter shown has a 30-0-30 uA range. Resolution is 1uA. Equates to 3mV DC Any DMM will resolve 0.1 mV. FOAD .... Phil
Field strength meter -- diode
Started by ●December 31, 2021
Reply by ●December 31, 20212021-12-31
Reply by ●December 31, 20212021-12-31
On Fri, 31 Dec 2021 17:59:02 -0800, Jeff Liebermann <jeffl@cruzio.com> wrote:>On Fri, 31 Dec 2021 16:19:49 -0800, John Larkin ><jlarkin@highland_atwork_technology.com> wrote: > >>On Fri, 31 Dec 2021 11:19:59 -0800 (PST), mkr5000 <mikerbgr@gmail.com> >>wrote: >>>Nothing could be simpler, an antenna, a coil and a 1N4148 diode but I'm seeing some schematics that have 2 diodes with one replacing the coil and the cathode connecting to the antenna. >>>Now that I'm old and stupid can someone tell me what that diode is doing please? > >>It's basically a 2-diode half-wave voltage doubler. > >Yep. More on how it works including an LTSpice model output (without >the actual model): ><http://k6jca.blogspot.com/2020/11/understanding-basic-rf-field-strength.html> > >>A low barrier schottky diode might work better than the germanium >>antique, especially at high frequencies. > >Yep. >"RF and microwave power detection with Schottky diodes" ><https://www.infineon.com/dgdl/Infineon-AN_1807_PL32_1808_132434_RF%20and%20microwave%20power%20detection%20-AN-v01_00-EN.pdf?fileId=5546d46265f064ff0166440727be1055> >The voltage doubler arrangement is Fig 15 (Pg 10).BAT15 is a nice part. Almost the same as an SMS7621. The circuit in fig 15 works better without RL. Go into a cmos opamp or comparator. The BAT15 has an Is of over 100 nA, so the diodes discharge the output cap when the signal goes away. That freaks some people out, which is always a good thing to do. https://www.dropbox.com/s/oz821ocx7d62lng/K420_Sig_Det.jpg?raw=1 -- I yam what I yam - Popeye
Reply by ●December 31, 20212021-12-31
whit3rd <whit3rd@gmail.com> wrote:> <https://usa.banggood.com/-30-0-30A-Galvanometer-Scientific-Current-Senso > r-Sensitive-Ammeter-Electric-Current-Detector-Analog-Display-p-1441415.ht > ml>The Richmeter RM109 resolves 1uV on the mV scale. With 100 ohms in parallel, it resolves I = E / R = 1e-6 / 100 = 10 nA. It doesn't drift. With 10 Megohms in parallel, it resolves 1e-6 / 1e7 = 100 Femtoamps. My favorite electrometer is the Kiethley 610C, which only goes down to 1e- 11 A full scale, and drifts like hell. The RM109 is $31.46 on Amazon Canada: https://www.amazon.ca/Alician-RICHMETERS-Multimeter-Backlight- Voltmeter/dp/B086VH3NNP/ It is probably cheaper on Amazon US. I can't find it on Banggood, but it is on Aliexpress for about the same price to Canada. However, beware of counterfeits on Asian sites. I have been burned badly. There is another model of the Richmeter that measures temperature. It is on a shelf I can't reach right now so I can't give you the model number. Here are the specs for the RM 109 True RMS Multimeter. DC Current: 60mA/600mA/10A DC Voltage: 999.9mV/9.999V/99.99V/750V AC Current: 60mA/600mA/10A AC Voltage: 999.9mV/9.999V/99.99V/999.9V Backlight Time: 120 Seconds Capacitance: 9.99nF/99.99nF/999.9nF/9.99uF/99.99uF/999.9uF/9.999MF Continuity: Yes Dimensions: 65x130x32 mm Diode Test: Yes Display Type: 4 1/2 digits Duty Cycle: 1%-99% Frequency: 99.99Hz/999.9Hz/9.999KHz/99.99KHz/999.9KHz/9.999MHz Operating Mode: Auto/Manual Ranging Operating Temperature: 0 - 40 Resistance: 99.99/999.9/9.999k/99.99k/999.9K/999.9M Special Function: Voltage Function have Low Frequency test function Square Wave Output: 50Hz/100Hz/200Hz/300Hz/400Hz/500Hz/600Hz/700Hz/800Hz/ 900Hz/1000Hz/200 For some bizarre reason they omit the mV range, which you can see on the Amazon site. It is third up from the OFF position. This is the range that gives 1uV resolution.
Reply by ●January 1, 20222022-01-01
Jan Frank wrote: ===============> > The Richmeter RM109 resolves 1uV on the mV scale. With 100 ohms in > parallel, it resolves I = E / R = 1e-6 / 100 = 10 nA. It doesn't drift. > > With 10 Megohms in parallel, it resolves 1e-6 / 1e7 = 100 Femtoamps. > > My favorite electrometer is the Kiethley 610C, which only goes down to 1e- > 11 A full scale, and drifts like hell. > > The RM109 is $31.46 on Amazon Canada:** See specs INCLUDING the 9.999 mV range. https://www.alibaba.com/product-detail/RICHMETERS-RM109-Palm-size-True-RMS_60768171490.html ..... Phil
Reply by ●January 1, 20222022-01-01
On Friday, December 31, 2021 at 6:12:44 PM UTC-8, palli...@gmail.com wrote:> whit3rd wrote:>> https://usa.banggood.com/-30-0-30A-Galvanometer-Scientific-Current-Sensor-Sensitive-Ammeter-Electric-Current-Detector-Analog-Display-p-1441415.html > > > > > A moving-needle meter for 30 uA with 100 ohms internal resistance > ** Such movement have around 3000 ohm R.Review the link. Internal resistance is marked as 100 ohms.> > can cover the 3mV range, with 30 uV easily resolved. > ** Horse poo.?? A needle that swings circa 100 mm, you can read to a millimeter or less.> The meter shown has a 30-0-30 uA range. > Resolution is 1uA.Not if you have normal eyesight. With a vernier scale, you can pick out a thousandth of an inch. Mirror scales help, too (though neither is on the depicted model). Anyone who ever used a slide rule knows to interpolate between marks.> Equates to 3mV DC > Any DMM will resolve 0.1 mV.Zero won't be accurate for analog or DMM either, but twitches of the meter might be more significant than a dancing last-digit of a digital display.
Reply by ●January 1, 20222022-01-01
Thirdwit Congenital LAIR whit3rd wrote: ================================ > >> > > A moving-needle meter for 30 uA with 100 ohms internal resistance > > > ** Such movement have around 3000 ohm R. > > Review the link. Internal resistance is marked as 100 ohms.** NO it is NOT !!!> > > can cover the 3mV range, with 30 uV easily resolved. > > ** Horse poo. > ??** Read my post - fuckwit.> A needle that swings circa 100 mm, you can read to > a millimeter or less.** One div is the resolution - at best.> > The meter shown has a 30-0-30 uA range. > > Resolution is 1uA.> Not if you have normal eyesight. With a vernier scale,** The meter has has no such damn thing, you fucking LIAR !!!,> you can pick out a thousandth of an inch.** You on drugs ? LSD maybe ?? Cocaine ?> > Equates to 3mV DC > > Any DMM will resolve 0.1 mV. > > Zero won't be accurate for analog or DMM either,** FFS what a DESPERATE LIAR you are !!!! FOAD you Dem pig.
Reply by ●January 1, 20222022-01-01
On Friday, December 31, 2021 at 9:11:25 PM UTC-8, palli...@gmail.com wrote:> whit3rd wrote:> > > The meter shown has a 30-0-30 uA range. > > > Resolution is 1uA. > > > Not if you have normal eyesight. With a vernier scale, > ** The meter has has no such damn thing, you fucking LIAR !!!, > > you can pick out a thousandth of an inch. > ** You on drugs ? LSD maybe ?? Cocaine ? > > > Equates to 3mV DC > > > Any DMM will resolve 0.1 mV. > > > > Zero won't be accurate for analog or DMM either,> ** FFS what a DESPERATE LIAR you are !!!!Read for content, not for vitriol; the reading on a microvolt-resolution instrument is only useful for thermocouple circuitry, OR for something in a stirred constant-temperature bath. Accuracy at that level is impossible where dissimilar metals and normal thermal gradients abound, but precision is another story, as is timing (like, looking at a cellphone sending a burst and causing a periodic brief twitch).
Reply by ●January 1, 20222022-01-01
Thirdwirt CONGENITAL LIAR : whit3rd vomityed: ===============================> > > > > The meter shown has a 30-0-30 uA range. > > > > Resolution is 1uA. > > > > > Not if you have normal eyesight. With a vernier scale, > > ** The meter has has no such damn thing, you fucking LIAR !!!, > > > you can pick out a thousandth of an inch. > > ** You on drugs ? LSD maybe ?? Cocaine ? > > > > Equates to 3mV DC > > > > Any DMM will resolve 0.1 mV. > > > > > > Zero won't be accurate for analog or DMM either, > > > ** FFS what a DESPERATE LIAR you are !!!! > > Read for content,** ROTFLMAO !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! BRAIN FUCKED Google monkeys like YOU cannot READ at all.> the reading on a microvolt-resolution** MASSIVE RED HERRING !!!!!!! Your mom was a drug addict and you are brain dead.
Reply by ●January 1, 20222022-01-01
In article <b623673b-5837-44c7-b53c-1515a6db9cfdn@googlegroups.com>, Rich S <richsulinengineer@gmail.com> wrote:>Though we could do much better, a modern choice, >for the opamp, instead of an LM3900. Like,Just remember that the LM3900 is a Norton amplifier, not a classic op amp with symmetrical inputs. You may be able to drop a standard "single supply" op amp into an LM3900 circuit without having to change things around, but possibly not.
Reply by ●January 1, 20222022-01-01
On a sunny day (Fri, 31 Dec 2021 19:09:23 -0800) it happened jlarkin@highlandsniptechnology.com wrote in <btgvsghggbcuhad95dj2u2jo1t1d218b8q@4ax.com>:>The circuit in fig 15 works better without RL. Go into a cmos opamp or >comparator. The BAT15 has an Is of over 100 nA, so the diodes >discharge the output cap when the signal goes away. > >That freaks some people out, which is always a good thing to do. > >https://www.dropbox.com/s/oz821ocx7d62lng/K420_Sig_Det.jpg?raw=1For a yes / no detector this model works for me: https://www.ebay.com/itm/313759590627?hash=item490d8768e3:g:31oAAOSwTdlhl2fr For more info on the source, if between 30 MHz and about 2 GHz: https://www.ebay.com/itm/272411458376 plenty of free spectrum analyzer software for it around. This uses an OLED: http://panteltje.com/pub/SWR_bridge_IMG_5051.JPG http://panteltje.com/pub/SWR_bridge_circuit_diagram_IMG_5053.JPG Not sure I published the code, the bridge idea is not mine: http://panteltje.com/pub/SWR_bridge_on_dummy_load_IMG_5046.JPG I have a more SWR stuff.
