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  1. F

    Audio limiter to quiet loud radio commercials

    Audioguru, Looking at your N-channel circuit I'm confused by the "from rectifier" at R4 and the "positive voltage" at the JFET source. I assume you are expect a full wave, 4 diode rectifier that produces both + and - voltages. Plus goes to the JFET source, and minus goes to R4. Do I have that...
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    Audio limiter to quiet loud radio commercials

    Audioguru, I setup my two-fet circuit onto the Internet radio and so-far I am disappointed with the performance. Under higher audio signal it does reduce the volume but sometimes it produces a little distortion. I think i can live with that. I'm still adjusting things and I'm still using my...
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    Audio limiter to quiet loud radio commercials

    Wow, Audioguru, thank you... Seeing your diagrams I lashed up a quick common source Jfet circuit and it does seem to turn on and off with both a positive and negative drain voltage, although not with equal vigor (that may have been mentioned in some prior notes). The turn on with a positive...
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    Audio limiter to quiet loud radio commercials

    1. I'm still struggling with how a single jfet can attenuate an audio bipolar signal without an external power supply. So glimpsing at articles that seem to say that MOSFETs are bidirectional and Jfets are unidirectional (I think), I thought maybe the Mosfet might apply to my problem. Judging...
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    Audio limiter to quiet loud radio commercials

    Audioguru, Thanks, I can use all the help I can get. Again, my FET knowledge is pretty rusty but I think I agree with most of your statements.. Yes, I plan on feeding the rectified audio DC which jumps from under 0.4v to over 1.0-1.5v with loud commercials. And I agree there will be some...
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    Audio limiter to quiet loud radio commercials

    Harold, Great idea..Although it's been about 45 years since I designed anything using a FET...Anyway I found this design (below link) that seems to fit my situation. I don't think I need that center FET because I think that's used to open the "perfect switch" and I need some conduction to hear...
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    Audio limiter to quiet loud radio commercials

    I lashed up a quick rectifier circuit on the audio channel and was pleasantly surprised that the DC voltage without a commercial was fairly steady at about 0.4 volts, however when a loud commercial came on it jumped to over one volt and stayed there, again pretty steady. Some commercials caused...
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    Audio limiter to quiet loud radio commercials

    Thanks, Audioguro, Yes, I agree my diodes will likely cause severe distortion....I don't think I would care for a commercial, but it's possible that would it be very annoying, Likewise I think I can cope with the slow recognition of the commercial, but if it cuts in and out that sounds bad. Frank
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    Audio limiter to quiet loud radio commercials

    Thanks, AK, Your circuit looks like it would do a good job for me, but I'm hoping for something simpler, without a need for a power supply. If i can't do it simple I may give your circuit a try. Frank
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    Audio limiter to quiet loud radio commercials

    Yes, good point about the "compression" factor...That probably is the situation since I did not see a big amplitude increase with the commercials...Although there was some increase in amplitude and I still want to fine tune the clipping diode technique, hopefully it will moderate the high volume...
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    Audio limiter to quiet loud radio commercials

    I have an internet radio who's volume gets annoyingly loud during some commercials and I am trying to figure out a simple way to automatically reduce that volume. The output of the radio goes to an amplifier via a standard headphone jack on the radio. So inserting a limiter of some kind in that...
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    Boiler thermocouple voltage monitor

    Alec_T, I'm going to buy a Hall effect sensor and give it a try. My adapter gives me access to the inner conductor of the thermocouple. Thanks, again, Frank
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    Boiler thermocouple voltage monitor

    A related question: Are there DC current sensors that don't require insertion into the circuit? Hall effect sensors? If so, that sounds pretty safe for this application, although they would have to operate at pretty low current levels. Thanks, Frank
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    Boiler thermocouple voltage monitor

    Thanks, Alec_t, I just did some tests on a spare gas valve that I have and it drops out at 3mv. my proposed circuit suggests a worse case fault only provides about 10uv across the gas valve (4.8v into a 0.1/50,000 ohm voltage divider) . So just about anyway you look at it should be safe. But in...
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    Boiler thermocouple voltage monitor

    I was planning on using the ADC input of an esp8266 microcontroller to monitor the voltage of my gas boiler's thermocouple. My main question is safety. How can I connect to the thermocouple without a safety issue. For example, if some failure happened that applies voltage to that thermocouple it...
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    Blocking DC voltage on an AC circuit

    It sounds like they have a dimmer control feeding a transformer based power supply for led lighting. I found this link that may explain a similar problem. http://www.lightingservicesinc.com/about-us/news-events/news/lutron-guide-to-dimming-low-voltage-lighting 2.Do not use regular...
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    WiFi enabled Garage Door Opener

    Sorry, i don't know anything about the relay you purchased. Anyway, connecting the magnet detector switch to your relay doesn't do any good if the software in your relay is not programmed to detect it. Best I can tell from a quick reading of the associated URL I didn't see any "input"...
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    WiFi enabled Garage Door Opener

    That looks like a Nodemcu board, but I don't think it is. It might employ an esp8266 but I don't think it's actually a Nodemcu....Although it might be a very similar concept. I'm not sure what programming language it uses but it looks like C++ and something called a Particle IDE. (not sure what...
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    WiFi enabled Garage Door Opener

    One way to do this is using an esp8266, or a Nodemcu module which contains an esp8266 with some nice extras. Both have wifi capabilities and can be programed using the Arduino Development software. You can find lot's of example projects on the web and probably some can be modified for your...
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    Any through-hole microcontrollers which are programmable via USB?

    I have been using an esp8266 based module called a nodemcu. It's Arduino compatible and uses the Arduino IDE. It has a micro usb connector that supplies power to the module, loads the pgms and supports diagnostic data. The exp8266 has built-in wifi. The nodemcu pinouts are breadboard compatible...
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