I'm tired of explaining to people that AC mains power effects audio gear.
So, what I want is a very cheap, effective device that I can buy/build that creates masses of audible hum, buzzing and noise when plugged into a mains power outlet near some audio gear.
Basically, I want to be able to say 'Here, plug this in next to your audio system and then tell me AC power has no effect...'
Any ideas?
Cheers,
Alex
So, what I want is a very cheap, effective device that I can buy/build that creates masses of audible hum, buzzing and noise when plugged into a mains power outlet near some audio gear.
Basically, I want to be able to say 'Here, plug this in next to your audio system and then tell me AC power has no effect...'
Any ideas?
Cheers,
Alex
Thanks, but a welder isn't practical and a programmable AC power supply is way out of scope budget wise.
Most electrical projects on diyaudio use mains power - so what I'm asking for presents no greater safety issues than any other project that uses AC mains.
What I was hoping for is some kind of plug-in oscillating circuit that feeds noise into the mains power outlet which can be heard through audio gear.
Essentially the exact opposite of what we normally try to achieve!
Cheers,
Alex
Most electrical projects on diyaudio use mains power - so what I'm asking for presents no greater safety issues than any other project that uses AC mains.
What I was hoping for is some kind of plug-in oscillating circuit that feeds noise into the mains power outlet which can be heard through audio gear.
Essentially the exact opposite of what we normally try to achieve!
Cheers,
Alex
Was thinking of something that can include it... and them some...
fluorescent lamp
Plus parallel enough of them and you might get enough surge to kill something.
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Hi Alex,
in a past life I worked for a firm that designed Gen Set controllers, due to the horrible mains around the world and trouble determining where the zero crossing was, we designed a dirty mains simulator for testing circuitry. Basicly we had a signal gernerator with the fundimental frequency + lots of nasty harmonics, this wired up a chip amp, the output of this put through a transformer to give us our mains voltage. Of course to get some current it is quite a large rig.
This was also used to test PSU's as it is during the inital stages of a PSU that you want to filter out this crud on the mains, if it gets through to the equipment you are asking for problems.
in a past life I worked for a firm that designed Gen Set controllers, due to the horrible mains around the world and trouble determining where the zero crossing was, we designed a dirty mains simulator for testing circuitry. Basicly we had a signal gernerator with the fundimental frequency + lots of nasty harmonics, this wired up a chip amp, the output of this put through a transformer to give us our mains voltage. Of course to get some current it is quite a large rig.
This was also used to test PSU's as it is during the inital stages of a PSU that you want to filter out this crud on the mains, if it gets through to the equipment you are asking for problems.
If your audio equipment is affected by mains variations... and in particular if you have audible hum/noise/crackles etc coming from the speakers when the mains is less than perfect then there is a problem with the design of the audio gear.
The only effect you may notice is buzzing of toroids due to harmonics on the mains, and that should cause no audible effects on the reproduced audio.
I know many will disagree on that but IMO if regulated PSU's are doing their job then the outputs are TOTALLY unaffected.
If ground wiring is correct again there should be no effect.
If unregulated supplies cause a power amp to sound audibly worse then the design isn't up to much with regard to PSU rejection etc.
Just my thoughts
Anyone with a turntable can tell you that AC mains affect audio equipment. That's why a turntable should not be plugged into a power strip, but a dedicated socket, if available, and away from televisions and such. You should try incorporating a phono cartridge into your device. That will surely pick up an audible hum, especially if you wired it into the audio equipment.
A big halogen bulb: at low dimmer settings, the filament will have a much lower resistance than at nominal power, and this will generate huge current spikes.
And if you want nasty noise into the earth connection, connect a 4.7nF Y cap between the earth and the A2 of the triac, before the suppressing choke.
Basicly its EMC problems. Unfortenatly not all equipment is EMC compatable (CE marked in the UK) and not all CE marked equipement has been tested, or corners have been cut. Trying to make your mains noisy may not endear you to your nieghbours. The best way of combating it is by design, as said earlier in the power supply, common mode chokes, filters etc, and also by circuit layout. A lot of noise (EMC related) is also present in the RF bands, mobile phones, wireless networks.
A big problem in the UK is data over mains!!! this is efectively adding noise and is causing a large number of problems and complaints.
It is a problem with todays widespread use of electronics, and needs to be factored in to designs, not only to avoid problems with your own designs, but also prevent EMC problems from your equipment adding to the problem.
For one project, the mains was that bad that up to the 13th harmonic was causing zero crossing detection errors, next to a large factory with variable speed drives for the HVAC.
A big problem in the UK is data over mains!!! this is efectively adding noise and is causing a large number of problems and complaints.
It is a problem with todays widespread use of electronics, and needs to be factored in to designs, not only to avoid problems with your own designs, but also prevent EMC problems from your equipment adding to the problem.
For one project, the mains was that bad that up to the 13th harmonic was causing zero crossing detection errors, next to a large factory with variable speed drives for the HVAC.
That reminds me, a user of HomePlug was complaining how he heard noises with some speakers.
Can't fit many fluorescent lamps inside into a metal box though, even if they're CFL. What produces the noise anyway, the power supply? Would it be possible to build one specially designed for producing noise?
I wonder if it's possible to make the earth noisy too.
The CFL uses a switch mode power supply -- one guy reported that when he switched on his garage CFL light the door opener would engage -- the CFL is a pox on humanity. Don't get me started....
I would say a microwave oven with a bent door would help.
You can still get spark gap generators, they will wreak all kinds of havoc! Like EMP.
Here in NJ we have some of the earliest utility wiring in the world, and thus some of the noisiest power lines under the sun.
G'day All,
Thanks for the replies and ideas. I actually didn't expect many responses to my unusual question.
Could you just use a small chip amp to inject some noise into mains (neutral or earth?) rather than powering the device from the amp itself?
The people I know don't have gear with properly designed regulated power supplies. So I only need a simple way to demonstrate the point that AC mains can effect audio gear.
This could be worth a try - the nastier, the better.
Hmmm. Spark gap generators - are these small and cheap?
Would EMP from spark gap generators be enough to damage audio gear? (or anything else).
I hope so. If it does, then it proves my point.
I've got a drill that throws sparks like crazy when it runs, so I'll try that too.
I was hoping for a device that had no audible sound of it's own - just the noise it generates clearly heard via the audio gear.
Cheers,
Alex
Thanks for the replies and ideas. I actually didn't expect many responses to my unusual question.
Could you just use a small chip amp to inject some noise into mains (neutral or earth?) rather than powering the device from the amp itself?
The people I know don't have gear with properly designed regulated power supplies. So I only need a simple way to demonstrate the point that AC mains can effect audio gear.
This could be worth a try - the nastier, the better.
Hmmm. Spark gap generators - are these small and cheap?
Would EMP from spark gap generators be enough to damage audio gear? (or anything else).
I hope so. If it does, then it proves my point.
I've got a drill that throws sparks like crazy when it runs, so I'll try that too.
I was hoping for a device that had no audible sound of it's own - just the noise it generates clearly heard via the audio gear.
Cheers,
Alex
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