DIYers and designers?

hairofthedawg · « **on:** 2 Jan 2003, 06:30 pm »

What types of test equipment do you use and what do you use each item for? I'm thinking about trying a few things and have a multimeter but am wondering if an o'scope, signal generator and spectrum analyzer are required for most projects. I have no idea what I'll be trying to build yet, just trying to plan ahead. Most of my experience has been with mil-spec test equipment and I know I don't want to spend that kind of money. A friend of mine has gotten some decent buys on scopes on e-bay. Is that the best place to purchase or are there other outlets you'd recommend? Any odd tools that wouldn't be found in a normal toolbox required?

cheers,

Dick

Bill Baker · « **Reply #1 on:** 10 Jan 2003, 05:57 pm »

Greetings Dick,
No matter what equipment you purchase in the future, the most important thing will be your ears. Especially if you are building speakers. After all is said and done, it will be [your] ears that will decide if your project was a sucess.
Good luck on your ventures.

hairofthedawg · « **Reply #2 on:** 10 Jan 2003, 06:42 pm »

Endicott? Spiedies? what I would do for one right now...thanks for the advice...just would like some backup aside from my ears... I'll probably just keep listening and not build anything, but who knows? I've got a pinball machine that needs my attention at the moment..

cheers,

Ever been to O's tavern?

Dick

Bill Baker · « **Reply #3 on:** 10 Jan 2003, 06:51 pm »

Hi Dick,
Are you from Endicott?? Just had a Lupos' spiede sup last night. Haven't been in O's Place in a while since Riverhouse Lanes shut down and I stopped bowling.

What type of project are you considering? Electronics or speakers?

Have fun with the pin ball machine.

hairofthedawg · « **Reply #4 on:** 11 Jan 2003, 03:22 am »

No, not from there, but I spent several week there on temporary duty while IBM was building one of the aircraft I worked on when in the Air Force...back in 86 I think. I ordered some of Lupos spiedie sauce online when I was in Korea, and while they were good when I made them, they didn't have that same magic....could be one of those memory things that make things better than they were, but I don't think so. I'm not sure why O's was our hangout, but I pretty much just went where the other guys went back then. Good wings and pizza!

I'm thinking more about electronics as far as building things, mainly because of my lack of woodworking skills and shipping costs. I'll eventually leave Cyprus and the less weight I have the better. The reason I asked the question was to find out how to measure the equipment I already have. It doesn't come with many specs and while I like the sound, I'd also like to know more about it. Most of my experience is with RF, radar jamming type stuff and while I'm sure the equipment and measurement method is similar, I don't have the bucks for the type of equipment the Air Force uses. I'll probably start with a simple tubed amp and preamp and go from there. I've got the equipment for building, I think, multimeter should be enough for that, but it's the measuring part that I don't know what equipment to use to measure.

cheers,

Dick

JohnR · « **Reply #5 on:** 11 Jan 2003, 03:44 am »

Hi Dick, I think you're right that you don't need much more than a reasonable DVM for building. I have an oscilloscope and hardly ever use it. For measurement, it sounds like you want something reasonably sophisticated, capable of distortion measurements and the like? I imagine that a PC-based system would be the way to go these days but I wouldn't know what

. I believe Curt of IRD has a very sophisticated PC-based system but I expect it's $$$. I would be very interested to hear if you find anything affordable along these lines.

mgalusha · « **Reply #6 on:** 11 Jan 2003, 03:49 am »

Dick,

A few things I have found very useful...

1) Variac or similar. Not exactly test equipment but being able to bring up the voltage slowly on a new project is reassuring.

2) Signal generator. Handy for many things. I use it to test phase, a signal for impedance measurements, square wave response, signal tracing.

3) Oscilloscope. In conjunction with the signal generator it's very useful. Even if the specs don't exactly define the sound it's nice to see that the output signal at least resembles the input.

4) AC voltmeter. Most DMM's don't measure high frequency AC very well. You can pick up a nice HP 400E analog voltmeter for $75 - $100 off of e-bay and other places on the web. Supposed to be good up to 4Mhz.

5) Frequency counter if your DMM doesn't have one. Very handy.

6) Some nice 4 and 8 ohm resistors for amplifier testing.

7) A logic probe - this is more for your pinball game. They are full of TTL IC's and when they fail it can really help.

Mike

hairofthedawg · « **Reply #7 on:** 11 Jan 2003, 04:16 am »

Thanks guys,

I've used a variac before and they are very nice, especially with the voltages I used to work with. I wish I had a photo of the capacitor bank I used to work on...talk about scary...enough voltage to arc a cesium lamp and yes, it knocked dick in the dirt a time or two

Would you rather have an oscilloscope or a spectrum analyzer? One of the funner jobs I've had was testing antennas and I used a network analyzer that would give you a chart of the resistance, capacitance and inductance of an antenna over the frequency range specified. I've always wondered if this would be useful with speakers. We had one in Korea, but I don't remember if it went down to audio frequencies.

Thanks, didn't realize, stupidly, that I would need to measure HF AC. I'm too lazy to go see what brand of fluke I have, but I'll check later.

For the pinball game, I don't know what I need. I have a motor that works sometime and sometimes not. Check this out...thing's hand in the addams family machine...when I have the playboard fully vertical everything works fine, move it slightly past vertical on the way down and the motor binds. It's not hitting anything, it just stops. It worked fine for 6 weeks then stopped. Actually it doesn't stop, just sits there trying to move up and wavers. It doesn't sound like the motor's stressing or anything, just looks like it's not strong enough to make it past the change in gravity when I move the playfield past vertical. My boss at work said motors can be that sensitive so unless I find someone else who can suggest a solution, I'll probably have to buy a new motor. The game plays fine though without it so I'm not super motivated to fix it

cheers,

Dick

darthVader · « **Reply #8 on:** 11 Jan 2003, 04:33 am »

You don't really have to measure HF AC. I bought it mostly for measuring frequency response. I wanted to measure the ouput of my amps at 20Khz and this seemed the cheapest solution that would be reasonably accurate.

As for spectrum analyzer vs oscilloscope. I would choose the 'scope. My reasoning is that I can measure many different things vs the spectrum analyzer. Of course I don't have access to a professional analyzer, so I may be talking out of my ass.

I did purchase a copy of "TrueRTA" from trueaudio.com. It's a software based 1/24th octave real time analyzer. It's driven from a sound card and calibrates itself to the card. I use it with a sound blaster extigy via a USB port and it works pretty well. I believe it was less than $100 for the software. It also contains a frequency generator (sine, white and pink) and a software based 'scope. Not bad for the price.

Perhaps the lubricant on the motor in the pinball game has thickend up. They are (as you know) very dirty and I can't imagine that can be good for a motor. It may just need a through cleaning.

Mike

Oops... Didn't mean to post as dv... just logged in to check some admin stuff.

DIYers and designers?

darthVader