Signal Generator

[mhburton]

Hi guys,
I am a master electrician by trade and work on industrial process control instrumentation and generating systems for a background. I have some basic electronics experience and can read a schematic. I want to learn and work on my own amps and electronics in general and possibly build 1 or 2 amps for projects while I pick your brains to help me through.
I was wondering what y'all recommend for test equipment. Specifically what brand & model signal generator would you recommend for injecting an audio signal into an amp. Also are there any special features I should look for in an oscilloscope. Brand model recommendations? Any other instruments I might find helpful in my quest?
I currently own a Fluke 787 DVM and have access to a Fluke 120 oscilloscope from work. We have a frequency generator at work I have used when working on our Turbines, but I wasn't able to get an output from the amp when using it, so I suspect I am using the wrong type inst.
Thanks a lot. This is an awesome resource.
Michael

[selloutrr]

20mhz dual trace Oscilloscpoe Tektronics, HP are the top brands

DVM - Fluke

Soldering iron - weller

You need a tone, sine wave generator that with produce 100hz, 1Khz, 10Khz. Minimum. a function generator is also handy (sine wave, square waze, etc.)

A dummy load. 2,4,8,16 ohms into 300watts+

Before you go off and buy equipment go to the local library and read up on what you will be doing and how to properly use the test equipment.
these items aren't cheap, but they are a lot less then buying the equipment you need to work on PCB based electronics.

If all you want to do is build you only need a soldering iron.

[xtian]

You're ahead of the game. We cheaper hackers (k, fine, speaking for myself) rely on a simple DMM and an iPhone and guitar for signal generation. Gets the job done!

[M Fowler]

Variac, DMM (several), dummy load (DIY), small speaker box, capacitor discharge stick (DIY), and capacitence meter to start with.

Add the cheaper Loadstar sinewave generator and a o'scope later.

Mark

[Super_Reverb]

Hi guys,
I was wondering what y'all recommend for test equipment. Specifically what brand & model signal generator would you recommend for injecting an audio signal into an amp. Also are there any special features I should look for in an oscilloscope. Brand model recommendations? Any other instruments I might find helpful in my quest?
Michael

I agree. This community is a great resource together with the crowd at Hoffman Amps. I have spent a lifetime designing electronic systems and integrated circuits for a major automotive supplier to big 3 auto OEMs, but there are guys here that spend their lives building and repairing commercially produced amps. They bring a lot of good insight and experience to the table.

My current lab rig includes a Tek 455 scope, B&K Precision signal generator and a couple of Fluke 8010A bench meters. Suggest looking on ebay for your equipment needs. I've found equipment from hospitals and universities, and garage/estate sales on the cheap.

In the big scheme of things, we can get by with very basic equipment as selloutrr, xtian and M Fowler suggested. Due to very limited bandwidth of guitar signals, we can get if done for cheap.

Be patient and you'll find some good prices. I just scored a nice capacitance meter for $25 + shp online. It's somewhat of a luxury, but, it's a hobby for me. My hobbies always run in the red

Make sure you plug into the amp input when you inject a signal into your rig: there's usually an input shorting metal tab on input jack to control open circuit noise.

Another suggestion is to use your ears as you build, debug, and repair amps. You nay already know this, but visible sine wave distortion seen on a scope is sometimes very good and sometimes bad. If your speaker output signal looks exactly like the sine wave you feed it, your amp will sound sterile, indeed.


cheers,

rob

[Andy Le Blanc]

You could build a tone generator as a first project

https://tubeamparchive.com/viewtopic.ph ... +occilator

wicked simple

You'd be surprised at how little you really need

A good solder iron A+#1

a basic DMM

And a good calculator

A good old fashion signal gen. that'll put out enough juice to do a OPT
test is a good thing
but you can use a very basic tone source and a cheap SS amp too.

dummy loads are handy for power testing,
if you can measure current over a 1 ohm resistor and aren't afraid of a
calculator, your most of the way there.

you can fab up nearly everything else if you have too, and there are
ok O scope shareware programs that are usable on trash cpu, free

[Super_Reverb]

Hi guys,
I was wondering what y'all recommend for test equipment. Specifically what brand & model signal generator would you recommend for injecting an audio signal into an amp. Also are there any special features I should look for in an oscilloscope. Brand model recommendations? Any other instruments I might find helpful in my quest?
Michael

I agree. This community is a great resource together with the crowd at Hoffman Amps. I have spent a lifetime designing electronic systems and integrated circuits for a major automotive supplier to big 3 auto OEMs, but there are guys here that spend their lives building and repairing commercially produced amps. They bring a lot of good insight and experience to the table.

My current lab rig includes a Tek 455 scope, B&K Precision signal generator and a couple of Fluke 8010A bench meters. Suggest looking on ebay for your equipment needs. I've found equipment from hospitals and universities, and garage/estate sales on the cheap.

In the big scheme of things, we can get by with very basic equipment as selloutrr, xtian and M Fowler suggested. Due to very limited bandwidth of guitar signals, we can get if done for cheap.

Be patient and you'll find some good prices. I just scored a nice capacitance meter for $25 + shp online. It's somewhat of a luxury, but, it's a hobby for me. My hobbies always run in the red

Make sure you plug into the amp input when you inject a signal into your rig: there's usually an input shorting metal tab on input jack to control open circuit noise.

Another suggestion is to use your ears as you build, debug, and repair amps. You nay already know this, but visible sine wave distortion seen on a scope is sometimes very good and sometimes bad. If your speaker output signal looks exactly like the sine wave you feed it, your amp will sound sterile, indeed.


cheers,

rob

[mhburton]

You could build a tone generator as a first project

https://tubeamparchive.com/viewtopic.ph ... +occilator

wicked simple

Thanks a lot guys for the feedback on test equip. I'll scope out eBay, since that is usually the first place I check. I have a lot of tools already with the exception of test equipment, and I even have a fair amount of that also. I am a hopeless tinkerer(sp?) and accumulate a lot of stuff, although I am rebuilding my supply and my house since we got burned out last August. The house & wood shop burned almost to the slab from someone installing incorrect romex in the attic above the kitchen when it was built back in in 1986.
<BR>
This tone generator looks like fun and useful too. Several years ago I built & etched my own circuit boards for a R/C airplane project I ran across in a R/C magazine. I built a on-board glow driver circuit to turn the voltage to the glow plug in the engine on/off depending on the throttle position signal from my radio. It was a pretty cool little device.<BR>

[selloutrr]

learn and undersand proper amp safety before you go tinkering around.

[Allynmey]

Go to Ebay! I bout a HP/Agilant 100MHz scope in near new condition with recent calibration for around $100.

HP/Agilant Function Generator for about $40 in the same condition.

I have some 200+ watt clarostat resistors for dummy loads (I sold some for around $14.00 some time ago)

Get a good iron (don't skimp) you'll be glad you did.

Sounds like you are all set in the DVM Dept.

[coolidge]

I have been quite happy with my B&K meters and cheap 20mhz scope. My sig gen is some off brand, gets the job done. 2nd the recommendation for a Weller soldering station, mine is digital, love that. I recently picked up a thermal wire stripper for teflon wire and I'm liking it for that and shielded wire stripping.

If you have big man hands like me you can't have enough hand tools, I have all manner of spring loaded cutters, long needle nose pliers, clamps, and tweezers, I'm like a surgeon swapping tools as I build because I can't get my hands down in there. Finally nothing beats a roll of blue masking tape to keep wires out of the way and be a third hand.

[Structo]

Yes having miniature wire cutters and small needle nose, nippers, angled needle nose, etc. are good to have when working on tube amps.

I have a small pair of diagonal cutters that I paid $30 for that fit in the palm of my hand. Spring loaded of course.
Everyday I use those I give thanks that I have them, really nice.

A quality set of screw drivers because you don't want to bugger up screw heads.

A really good DVM, auto ranging, nice to have a capacitance meter in it as well.
True RMS reading.

Different probe tips with alligator clips or wire clips.
Usually the probe sets that come with most meters are junk.
Probe Master carries some nice sets.

I really need to pick up a Oscilloscope some day but I never see the deals some of you mention, like $100 for a 100MHz scope? Man that would be nice.
A decent sig gen would be good.

A variac can be a handy device.

A good soldering station is a must.
I swear there is almost a pound of solder in a Dumble clone.

Use the good eutetic solder (63/37), it sets up faster for good connections.

I like the small dia stuff like .031"