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Dave <theschemer@...> added the photo album Lorex Wifi Camera : An image of the circuit board of my Lorex Wifi security camera that has lost it's effective range. The following photos have been uploaded to the Lorex Wifi Camera photo album of the [email protected] group. Wifi Camera.jpg By: Dave <theschemer@...>

Hello , I have a single ended PID and a vccs driver (differential ) What is the best way to connect the two, so the PID output will be driver input? Thanks. /g/electronics101/photo/296358/3889903?p=Created%2C%2C%2C20%2C2%2C0%2C0 /g/electronics101/photo/296358/3889904?p=Created%2C%2C%2C20%2C2%2C0%2C0

First, I have no financial stake in Electronic Goldmine, I'm just a satisfied customer. I needed some transformers for a special project and Electronic Goldmine started offering these. Microtran Pico Transformer PM34-M Miniature 600 Ohm C.T. to 600 Ohm C.T. 50mW Rating "Microtran Pico transformer type PM34-M is a miniature fully encapsulated 50mW rated 600 Ohm C.T. to 600 Ohm C.T. transformer. Frequency response is ±2db 300Hz to 100KHz. Has 6 full length leads. Size only 0.3" x 0.4" x 0.425" tall. New" at https://theelectronicgoldmine.com/products/g28678 Full specs can be found here https://www.technicalaudio.com/pdf/MicroTran/Microtran_miniature_transformers_catalog_1974.pdf Electronic Goldmine offers surplus, new old stock, components and probably doesn't have oodles of these. 60Hz appears be just over -3dB. YMWV depending on your system. Short pulses of 1 cycle or 1kHz show minimum ringing. These could be ideal for coupling a computer to a ham/shortwave radio, PA, or other interface needs.

does anyone know if these ( cCTI OCXO type OSC5A2B02_can work at different frequencys if the internal crystal is swapped for a different freq item?.

Hi , I have reports of distorted tx audio on my ft-767DX,is it possible to feed audio from my laptop headphone jack into the rig mic input, then tx the laptop audio into a dummy load via the radio then monitor the transmitted audio via a diode detector using a crystal earpiece while i make adjustments?.

This might be of interest to radio enthusiasts in this group. Cable TV systems have always had problems with RF leaking from and into their "closed systems." This is a bit one sided industry view that is nonetheless interesting. Read all 3 parts and then the Distributed Access Architecture. https://blog.viavisolutions.com/2019/08/28/how-air-force-one-forever-changed-cable/ At one point the local cable system used a pilot tone smack dab in the middle of the 2M ham band to set the automatic gain of their 'gazillion' line amplifiers. Their system leaked like a sieve and a group of local hams sat up an impromptu network on that frequency, which shut the entire cable TV system down. The cable system was violating the law with excessive leakage. The same technical flaws that result in leakage that allow radiation of cable TV signals also allows external RF to get in. The cable system issued vague veiled legal threats, which resulted in the FCC paying them a visit with an order "Clean up your act, now." The spent a not so small fortune upgrading their system. it took them less than a month. The engineers I worked with (and me) were offered nearly obscene amounts of money to pitch in. They needed more warm bodies with technical skill than exist in Was it a mean nasty act on the part of hams? The answer depends on which side of the fence you are on. Similarly, in the early 1980s the Grateful Dead played a concert in Lexington, their roadies made the mistake of using 70cm ham radio transceivers, which really upset the local ham radio community. Which lead to another impromptu net on the roadie frequency. They tried to change frequencies but the hams followed. The roadies finally gave up and did the setup the old fashioned way. The take away here is hams are tenacious bulldogs with rabies and an attitude when it comes to guarding/protecting their frequencies.

what buffer amp do i need to connect my sdr to my yaesu ft-707 to use it as a panadaptor,i am looking for a cct diagram so i can homebrew something,thanks.

Lost the battle of yard lights. Now we have a plethora of dollar store rejects hiding amongst the weeds. Neighbor was very appreciative of the copper 120vac lights. Beautiful fixtures after stripping, polishing and spraying a lacquer. Looks fantastic, so isn't my handiwork. Next project needs to be / remain battery powered, naturally selected Headway 38120 LFP cells. 3.2v 8ah (yes, *8aH*) with max rated discharge of 15C (120A). Since I have about 50 of the darn things, gonna use a few of them. Except can't find a single cell lfp bms / battery disconnect. 2S hard to find as well, unless direct from China Mainland. Load anticipated around 10w (max, pwm), basically a string of low voltage lighting. Solar panel is 6v-ish, feeds a epoxy-encased charge circuit that in turn charges an INR lithium 3.7v cell 3000mwh capacity, or about 900mAh. I can knock down pv voltage (currently) by shading cells, eventually rewire each half in parallel. PV cell output is (educated guesstimate) 6-ish vdc @ 2w. I do have a dozen or so of the PV panels. Still leaves me with discharge issue. If cells go under 2.5v, damage occurs. LED string becomes dark around 1.9v and current falls to a few mA. If I put a usual and typical silicon diode in series with cell output to led string, I expect a .7-ish V across diode. Add that to 1.9v string conductance threshold, and have a 2.6V drop, which should halt any appreciable current flow at under 2.5v.. Does this course of reasoning have merit, or shall I remain in the Dark Side? ~SD

On the subject of antennas: Lo-VFH pager antennas surprisingly are using the person’s body as the antenna. The body “antenna’ couples into the pager’s internal antenna when it is when worn on the belt. Worse performance if used in the shirt pocket. Motorola’s Pageboy 2 series use the U-shaped metal case as the antenna. I have spent too many weeks optimizing antennas and front-end designs for the Motorola pagers. From low band-VFH-UHF and finally the first 900MHz pager. I like the info on the active antennas, and I am itching to build one. I got an SDR that I played with 5-6 years ago, but I have to relearn how to use it, or maybe get an updated unit. Bertho

Hello, I have a mixer shown in the link below.The way I calculate the noise coming out of the mixer is as following: -174+NF-conversion loss=-174+0.5-6=-179.5dB/Hz so far I am correct? also the Mixer Noise Figure typically measures within +0.5 dB of conversion loss for IF frequencies greater than 5 MHz. However I was told that we add another 3dB because we convert noise from RF twice. If its true, Is there some visualisation I could use to see why we add another 3dB? Thanks. https://markimicrowave.com/products/microstrip/mixers/m1-0818ne-1/datasheet/

First I consider Astron power supplies to be over rated and exist only because "hams have always used them." I'm amazed [really more dismayed] they get decent reviews. There are too many deficiencies to list, so I'll only list 3 1) Astron uses Intermittent Commercial and Amateur Service (ICAS) in their specs, if you are lucky you can find the Continuous Commercial Service (CCS) current, the CCS is typically about 60 to 70% and take the CCS rating with a huge block of salt. To begin with, to achieve CSS one must provide forced air across the heatsink, this won't help the power transformer, which can fail spectacularly. 2) Astron uses the uA723 regulator, a fine regulator even if it is 50 years old. However Astron, like most users of the uA723 never read, or at least never understood, the original spec sheet requirements for feedback capacitor and ~1k series resistor to protect the current sense input. Leave that resistor out and you will pop a uA723 faster then you'd believe. This is based on personal experience with home made uA723 power supplies and Astrons at 2 jobs. 3) Astron occasionally parallels silicon rectifiers. This is such a bit no-no I ought to use 60 point font with flashing red. As an experiment, obtain two identical, by identical I mean 2 rectifiers from the same manufacturer with the same date code. Places a 1 ohm resistor in series with each, force 10A, ~5A through each, and measure the voltage drop across the diodes. They will NOT match. The diode with the lowest voltage drop will hog most of the current and can overheat. Buy a diode with a higher, the proper, current value. This is a link to a popular Astron linear power supply. https://www.repeater-builder.com/astron/pdf/qst-2005-12-pg56-57-power-supply-analysis.pdf It is a litany of how to build a commercial product with a great return for near the absolute minimum skill and design quality but not a diagram for a power supply I'd consider acceptable. My 4th bone of contention is Astron uses way too low value for filter capacitor. I'd go with at least twice, probably 4 times. And my 5th bone of contention is their overvoltage crowbar sucks, it was obsolete in 1960 and is prone to false firing and also failing to trip when there was an actual overvoltage. A real world experiences, an Astron linear power supply overvoltage failed to trip and fried a 5K video effects unit, Note: The system existed when I was hired, I never saw the plans until the day the magic smoke escaped from the video effects unit. I had difficulty keeping my mouth shut and not screaming "What f-ing moron designed this system!" However after 40ish years working for idiots, I've learned to keep my mouth shut. My fault diagnosis, autopsy for what happened, led to an engineer suddenly leaving for greener pastures. I had a friend edit and basically rewrite my report so it didn't catch fire. It was still so brutal the agency legal department took me to task, I flatly stated I can prove every statement I made and feel free to fire me for telling the truth, "But I bet HR in Frankfort will disagree." They backed off. I've been called a pitbull with an attitude. I'll proudly accept that label when it comes the truth in any form.. If you want a good linear power supply, look to Lambda for high end, 100% reliable and expect to pay premium, For generally reliable, especially if you add a decent overvoltage crowbar, look to Bel Power Solutions linear power supplies. Bel has gone through several names changes, they were Condor, Power One, Power CA (or Power California). I've purchased several off Ebay and they all met original specs, even those 30 years old. The biggest weakness is the silicon heat sink compound dries out and the main filter capacitor can dry out. Condor, Power One, Power CA (or Power California) also to vastly overrate their power supplies, and will require force air ventilation! They use the chassis as the heat sink, no real heatsink with dedicated fins. Note 2: I only use switch mode power supplies for non critical loads/systems and only when they can't be replaced with linear

Perhaps someone here can help - looking for some advice on programming a DQ48F010 and PQ28C65 (flash/EEPROM roms) via a Willem 5.0 programmer - they are not listed (as far as I can see) in the supported device list. Please feel free to point me to an active forum for the subject. I suspect that it may be possible to configure the beast for them via the jumpers/switches - perhaps some kind person can provide advice as to how to go about doing this?? Changing the device to something that is supported in not an option as is buying a new programmer unless it is very cheap/free (I am a pensioner). Regards, Dave

I am using an SI5351 to generate 10Mhz and 100Mhz digital reference signals via 50ohm 5m long BNC cables but the SI5351 seems to struggle producing a reasonable square waveform at 10Mhz. What would be the best buffer circuit for this application? and could the same work for 100Mhz ?? Regards, Dave

"Investigation_and_Reduction_of_EMI_Noise_Due_to_the_Reverse_Recovery_Currents_of_50_60_Hz_Diode_Rectifiers.pdf" Abstract—Alternating current (ac)/ Direct current (dc) power converters with dc-bus filters can achieve high power density, however, it was found in this article that the reverse recovery currents of the 50/60 Hz diode bridge can lead to significant electromagnetic interference (EMI) noise violating EMI standards above 150 kHz. This article analyzed and quantified the mechanism of the EMI generation due to the reverse recovery currents of the 50/60 Hz diodes. It was found that although the reverse recovery of the 50/60 Hz diode bridge repeats at a frequency of 50/60 Hz, the EMI can be very high above 150 kHz due to the operating principle of electromagnetic compatibility spectrum analyzers. Two techniques were proposed to reduce the EMI due to the reverse recovery of the diode bridge. The analyses were validated by either simulations or experiments. Note: The 150kHz upper limit is extremely optimistic. I've had 1968 1N4004 diodes produce commutation EMI up to above 10MHz. Pretty intense too.

I've added another file to "Diode Commutation EMI" folder. "Shortwave Hum" is a real world explanation of how bypassing diodes can reduce SW Hum and intermodulation, I copied the web page at http://www.ll-leasing.com/pritch/shortwav.htm to a PDF "Shortwave Hum." I could quibble at some of the non technical, not quite accurate, information, but the webpage is a practical 'how to' based on the author's personal experience with linear wall warts. If you have a switchmode power supply wall wart, you are doomed.

I've added a folder "Diode Commutation EMI" that explain the causes of diode commutation EMI and steps to mitigate it. There are other solutions today, special diodes with controlled turn off characteristics exist, There are soft turn off diodes, and, oddly enough, fast recovery diodes. I suspect there are others but those are the only two I have any experience with. The "MicroSemi 302 Rectifier Reverse Switching Performance EMI" is extremely detailed. I wish I'd had this paper in 1974.

Hello , I am assembling the bits and peaces of what I learned and trying to implement them into my mixer shown in the link below. there is the -174+10log10(BW) of the component my mixer is 10GHZ so its -174+100=-74 also the is conversion loss which affects the noise level. The harder thing for me to understand is the modulation affects because we can put unwanted spurs into our working band which could also ruin the SNR. Is there some mathmatical example I could use to assmeble all these factors together? https://markimicrowave.com/products/microstrip/mixers/m1-0818ne-1/datasheet/ Thanks.

When a member of our shortwave listener club showed me a PA0RDT active E-Probe antenna I almost giggled, being polite I didn't giggle. However I thought "Well PT Barnum was right...one is born every minute." Then we mounted the antenna and gave it a test swirl. And I was stunned. I won't bother listing the details of the PA0RDT Mini Whip, plans are all over the net, http://www.kiwisdr.com/docs/pa0rdt_whip.pdf This is one interesting variant https://www.pa3fwm.nl/projects/miniwhip/ A good overview https://web.archive.org/web/20230722120107/https://www.g8jnj.net/activeantennas.htm Note: It is critical to understand how an E-Field probe antenna works! It must be installed properly or it will perform badly. Properly is a bit complicated but easier then erecting a 'real SW antenna" [to mean a 100 foot wire antenna at least 30 feet off the ground.[ <especially when you are 73> All E-Field Probe antennas are a compromise but have their place in the grand scheme of things. I have several, one optimised for 'audio' [whistlers] through ELF, one for ELF to LF, one for LF to 30MHz, although I m not interested in much above 20MHz. 11Meters from truckers is a good way to test any antenna. Prepare to be frustrated but E-Field Probe antennas do have their place and can offer surprising reception and will also drive you crazy getting there.

I found a stash of 5 'new old stock' 5CP1 5 inch oscilloscope CRTs at my parent's home. The new owners called my sister and told her they found a box of "electrical junk" under the eves. I went over, collected the boxes, thanked them and wondered what the heck I was going to do with 5CP1s? Then I remembered my ham radio RTTY (radio teletype) enthusiast who uses a CRT to tune for best reception. This guy is old school, mechanical RTTY terminals, etc. He bought an Owon AS-201 "retro" scope. This is a accurate review, roses and warts. https://chinese-electronics-products-tested.blogspot.com/p/as201-benchtop-oscilloscope-tested.html My friend wasn't happy with the AS-201, I thought it was nice when I checked it out, sort of primitive, but the X/Y offers excellent Lissajous Pattern display. I've had a fondness for Lissajous display since I made my first 'scope from a BW TV when I was 12. I pulled the deflection yoke, replaced it with one that fit, I had no idea about impedances, fed the output of my stereo to the H/V and the weird pattern mesmerized me. So I called him and explained "I have 5 WWII surplus CRTs... wanna trade?" I'm pretty sure he broke the speed limit getting here, so I'm not the proud, if doubtful, owner of an Owon AS-201. It really is a nice, basic, emphasis on basic, 'scope. FWIW, I strongly suggest anyone considering the Owon AS-201 think it over, for a few dollars more you can get a modern DSO with many more, better, options. Since my Owon AS-201 is basically "found on the side of the road" I got a heck of a deal. He who dies with the most test equipment.... wasted a lot of money.

All sorts of stuff: https://mysite.du.edu/~etuttle/electron/elecindx.htm -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, a critter that can be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin