[QUOTE=Tezzanator92;42012117]I'm going to use one of the 8 and 4.5 Ohm resistors for a reactive load once I've found a design I like. The addition of a speaker is a little bit of an experiment, I'm interested to see how useful it is. At the very least it should be an instant indication if the amp is clipping early or if a channel gets progressively worse as the temperature climbs.
The resistive load for me is more about giving me peace of mind that a repair I have carried out will be stable once it's out in the field. At the moment I have nothing except high power PA speakers to test with and I don't think my neighbours will like me much longer if I keep testing these things!
The next project is a small audio-range line level sine wave generator,[/QUOTE]
An active load would probably be just as good and more importantly adjustable, impedance in a real speaker varies very much with frequency which is not very well simulated by a resistor, an alternative that works very well is to take a speaker and cut out the cone that way you get no noise and the performance of a real speaker.
As for a sine wave generator I highly recommend you use a wien bridge oscillator, I also suggest a triangle generator as well which makes spotting clipping and non-linearity very easy, if you want even more fancy build a sweep generator in as well to measure the frequency response.
[QUOTE=nuttyboffin;42011949]Heres a much cheaper way of doing it, you can also test much higher powers:
Take a bucket of water,
put the wires in with a current meter in series with one of them.
Next, add salt until you reach the correct current.
????
Testing complete :)
You could also take 2 wires with a speaker and move them around in the bucket so you can hear as the bucket would really act like a resistor.[/QUOTE]
I, for one, absolutely LOVE producing toxic chlorine gas and caustic sodium hydroxide solution when attempting to simulate a resistive load!
The chlorine's dissipated into the water. You're just making clean water and slightly flammable gases (though not enough enough to be dangerous if you're not capturing them or something dumb). And electrolysis will only work at high voltages and amperage. I work with commercial pool chlorinators that use this.
tl;dr: nothing'll happen
[QUOTE=Agent766;42018058]The chlorine's dissipated into the water. You're just making clean water and slightly flammable gases (though not enough enough to be dangerous if you're not capturing them or something dumb). And electrolysis will only work at high voltages and amperage. I work with commercial pool chlorinators that use this.
tl;dr: nothing'll happen[/QUOTE]
What type metal is used in commercial pool chlorinators?
[QUOTE=Agent766;42018058]The chlorine's dissipated into the water. You're just making clean water and slightly flammable gases (though not enough enough to be dangerous if you're not capturing them or something dumb). And electrolysis will only work at high voltages and amperage. I work with commercial pool chlorinators that use this.
tl;dr: nothing'll happen[/QUOTE]
Most likely the electrodes will dissolve rather fast.
[QUOTE=SubbyV-2;42018147]What type metal is used in commercial pool chlorinators?[/QUOTE]
I have no idea off the top of my head.
[QUOTE=DrDevil;42018179]Most likely the cathodes will dissolve rather fast.[/QUOTE]
should last for a good while, enough to do any load testing needed. (tried and proven)
Electrolysis of salt water does produce sodium hydroxide and depending on what your using as cathode and anode materials stuff like copper chloride, ferric chloride, aluminium hydroxide, etc.
The results in a smelly mess if you run it for any length of time, there are a few ways around it such as using carbon or platinum electrodes, or instead of salt using sodium hydroxide which does not produce chlorine.
I'd rather just build an electronic load with a transistor and an op-amp.
Not to mention that a bucket of water is neither really precise, controllable, nor linear.
I should put a picture on my business cards of me testing amplifiers with a massive vat of saline water. Haha.
Thanks for the suggestions Chryseus! :)
Sitting here replacing axial capacitors with radials.
Fun.
What do you chaps think of these [url]http://au.element14.com/jsp/search/productdetail.jsp?sku=3708457[/url] in comparison of these [url]http://www.jaycar.com.au/productView.asp?ID=CW2196&form=CAT2&SUBCATID=1008#4[/url] or [url]http://au.element14.com/pro-signal/55-1205/woofer-poly-paper-cone-8ohm-5-25/dp/4262438[/url]
I want to make some over exaggerated bass monitors
Hit major paydirt at work this week. Got 2 more of those 3-phase speed controllers (with those delicious IGBTs in them), lots of old furnace boards (with PIC16s on them, though some have CEPP-somethingorother on them, no results from Google on what they are yet), and plenty of old thermostats with PICs, ATMEGA32s, and yet more of those ones I mentioned earlier with the fuck-huge manuals. Also got some sort of switch board/router dating back to 1989, has an MC6802, an EPROM and some kind of RAM chip in it, all through-hole.
[QUOTE=SubbyV-2;42027518]What do you chaps think of these [url]http://au.element14.com/jsp/search/productdetail.jsp?sku=3708457[/url] in comparison of these [url]http://www.jaycar.com.au/productView.asp?ID=CW2196&form=CAT2&SUBCATID=1008#4[/url] or [url]http://au.element14.com/pro-signal/55-1205/woofer-poly-paper-cone-8ohm-5-25/dp/4262438[/url]
I want to make some over exaggerated bass monitors[/QUOTE]
My Audiophile sense tells to buy the most expensive, as it clearly must be the best.
I've been sorting out my workbench and general "Tinkering" area and I have decided I want to buy my first "proper" oscilloscope. I know a couple of years ago the Rigol DS1052E was a favorite for a budget digital 'scope. Is this still a good choice or have better things come out since then?
I'm trying to decide whether to go for [url=http://www.ebay.co.uk/itm/Rigol-DS1052E-Digital-Oscilloscope-50MHz-1-GSa-sec-2-channels-plus-USB-storage-/280915462875?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item4167ddcadb]this[/url] - I want to buy from a UK supplier.
I'm only interested in measuring audio signals so I suppose bandwidth isn't a massive concern.
Any Ideas? Option two is a second hand analogue 'scope.
I personally have 2x used 2-channel Analogue oscilliscopes, work a treat for all i need to do.
I dont really trust the Rigol brand too much, have you seen their latest PSU?
[media]http://www.youtube.com/watch?v=y-KkPLWZJko[/media]
EDIT:
Then again... he is using A RIGOL Oscilliscope..
Aye, Don't think I've missed a single EEVBlog video. Silly mistake.
There's a guy on the EEVBlog forum flogging some Hitachi V-552s for £80 a pop (2 Channel Analogue, 50Mhz) - I think I'll go for one of these and pick up some probes off ebay :)
Yeah I'd recommend analog over digital in most cases, digital isn't really worth it unless your getting something high end, that said digital has some advantages but for audio work analog is better.
[QUOTE=Tezzanator92;42033584]Aye, Don't think I've missed a single EEVBlog video. Silly mistake.
There's a guy on the EEVBlog forum flogging some Hitachi V-552s for £80 a pop (2 Channel Analogue, 50Mhz) - I think I'll go for one of these and pick up some probes off ebay :)[/QUOTE]
I'd sell you my Iwatsu scope if shipping to the UK didn't cost as much as the scope itself.
I don't get why shipping is so damn expensive, I can buy shit off of some bloke in china who can ship it in a small box or padded envelope for FREE, but woe me if I try to ship a function gen to ddrl they want 45 fucking euro for a 2kg package the size of a shoe box.
I bought a pack of 100 white LEDs for ~90 pence deliveredonce. They were all individually wrapped in little plastic bags with a sticker and an SKU number, then in a big cardboard box.
Such a colossal waste of packaging, took me AGES to unwrap each LED to put into my storage. But how can they deliver such a box of LEDs so cheap and still make a reasonable profit?!
Anyway, I've bought one of those Hitachi 'scopes, just need some probes now :)
Looking forward to getting back into the swing of things, I've been too busy and my utility room has been in such tip I just haven't touched electronics in ages despite having the gear.
Digital scopes definitely are worth the money if you are looking at odd waveforms (data signals for example), which won't repeat.
[QUOTE=Tezzanator92;42034932]I bought a pack of 100 white LEDs for ~90 pence deliveredonce. They were all individually wrapped in little plastic bags with a sticker and an SKU number, then in a big cardboard box.
Such a colossal waste of packaging, took me AGES to unwrap each LED to put into my storage. But how can they deliver such a box of LEDs so cheap and still make a reasonable profit?!
Anyway, I've bought one of those Hitachi 'scopes, just need some probes now :)
Looking forward to getting back into the swing of things, I've been too busy and my utility room has been in such tip I just haven't touched electronics in ages despite having the gear.[/QUOTE]
I have the 100MHz version of [url]http://dx.com/p/p6060-oscilloscope-probes-pair-120cm-length-101452[/url] and they are quite nice for the price, in my opinion quite a bit better than the probes that come with the Rigol DS1052E. However if you do decide to go with these probes I'd suggest getting the 100 MHz version because you have a 50 MHz scope and, you know, China.
[QUOTE=DrDevil;42035065]Digital scopes definitely are worth the money if you are looking at odd waveforms (data signals for example), which won't repeat.[/QUOTE]
Tektronix has a few analog scopes with a triggered memory option. They're also pretty damn cheap too if you look. Beyond that I just recommend you buy a logic analyzer.
ooh, I can sell a digital logic analyzer. I'd love to get rid of it.
(though shipping'll be a bitch)
[QUOTE=pentium;42036829]Tektronix has a few analog scopes with a triggered memory option. They're also pretty damn cheap too if you look. Beyond that I just recommend you buy a logic analyzer.[/QUOTE]
Not every signal is a logic signal.
[editline]1st September 2013[/editline]
For example, good luck at looking at the shutdown characteristics of a power supply with an analog scope.
With the new generation of digital scopes, I see no advantages of an analog scope, over for an example the Rigol DS2072. And it's less than 850 euro's shipped anywhere in EU (from EU, so no extra taxes) and with 2 x 350MHz probes, so it's not unaffordable.
[QUOTE=BuG;42041857]With the new generation of digital scopes, I see no advantages of an analog scope, over for an example the Rigol DS2072. And it's less than 850 euro's shipped anywhere in EU (from EU, so no extra taxes) and with 2 x 350MHz probes, so it's not unaffordable.[/QUOTE]
I'm not sure I'd spend that much for a rigol scope, but the cheaper lower end scopes definitely are worth their money.
[QUOTE=BuG;42041857]With the new generation of digital scopes, I see no advantages of an analog scope, over for an example the Rigol DS2072. And it's less than 850 euro's shipped anywhere in EU (from EU, so no extra taxes) and with 2 x 350MHz probes, so it's not unaffordable.[/QUOTE]
If you are only doing basic audio work and just want to see a signal, an analog oscilloscope is probably the best, and cheapest, way to go since you can pick them up for almost for free if you look around.
[QUOTE=BuG;42041857]With the new generation of digital scopes, I see no advantages of an analog scope, over for an example the Rigol DS2072. And it's less than 850 euro's shipped anywhere in EU (from EU, so no extra taxes) and with 2 x 350MHz probes, so it's not unaffordable.[/QUOTE]
Only 850 euro's ?
Please give us some of your money.
What is the difference between a 1/4 and 1/2 watt resistor?
Sorry, you need to Log In to post a reply to this thread.
