Oh, some small things:
A small patch panel on the bench riser for convenient connections to my loads, my main bench speakers, a low power drive signal from my little shop stereo amp. Then patch cords hanging nearby.
Each load/speaker/source has a dual banana 5-way post and a parallel 1/4" female. (I service pro-audio gear) My patch cords all have a dual banana male on one end. Other ends might have bare wire, 1/4" male, RCA male (for cheap stereos), and others.
And for occasions - a couple 12" long dual banana male to male patch cords. I can connect a couple of patch points together. For example to parallel two load resistors.
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A little Fostex TT-15 tone generator for test signals when i am not near the bench.
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Mine is commercial, but a cable tester can be easily built. I can plug in a patch cord - like an RCA to RCA cord - and it tells me if the thing is open or shorted. I could do that with a meter easily enough, but with this I can yank and flex the cords to look for intermittants. Not so easy to do that with meter probes.
My little Whirlwind model is basic, but it allows not only say RCA to RCA cords to test, but you can also test RCA-1/4" or even XLR to one of those. It will also check phase reversal in an XLR cable.
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I don't use one of those little curve tracers, but I know a lot of techs who swear by them. You COULD spend over a thousand dollars for a Huntron Tracker or something, but for the price of a tiny transformer and a couple resistors stuffed in a little project box, you can make your own. Does require your scope be X-Y capable.
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If you are in pro audio, those plastic nuts on the Cliff jacks can be tough to grab with pliers. Go to the hardware and get a 15mm deep socket. Instant hand wrench for the nuts. (Deep sockets are sockets for a socket wrench that are maybe 65mm long. I don;t know if they have a different name elsewhere inthe world.)
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A magnifying glass. I have one with a stand - like those little stands that support a couple clips to hold things for soldering. I use it all day long. Set it there and hands free I can do close sodler work without tying up a hand.
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A 9v battery is a quick and reliable go/no-go tester for a speaker.
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A Dremel tool. Geez I use this thing all the time.
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One little thing I love is my "FybeRglass" brush eraser.
http://www.eraser.com/catalog.cgi?pt=&mode=details&category_id=&product_id=1222&
This thing is a little stiff brush originally made as an ink eraser for draftsmen, but it is a mild abrasive that is great on all manner of circuit board and other needs. They also come in brass bristles and stainless bristles. But the fiberglass is softer than the copper on a circuit board. You can scour away conformal coatings or even just shine away oxidation on exposed copper. Dirty edge connectors? No problem. Doesn't hurt the metal.
As the brush wears away, you advance it with the screw. When it wears out, you stick a new brush refill in it.
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A death cord. Simply an AC power cord with alligator clips on the end. Allows you to connect the mains to something. Good for checking loose power transformers or partial systems. For example I can power up a switching supply out of its host equipment
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A volume control in a box. Just a little project box with a pot in it. A couple jacks for in and out. Occasionally useful if I want to play with the level of something.
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A switched outlet for the unit under test on your bench is a common accessory, but i find having an ammeter on it adds to its value.
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A small DC power supply - good for checking relays and things.
A small patch panel on the bench riser for convenient connections to my loads, my main bench speakers, a low power drive signal from my little shop stereo amp. Then patch cords hanging nearby.
Each load/speaker/source has a dual banana 5-way post and a parallel 1/4" female. (I service pro-audio gear) My patch cords all have a dual banana male on one end. Other ends might have bare wire, 1/4" male, RCA male (for cheap stereos), and others.
And for occasions - a couple 12" long dual banana male to male patch cords. I can connect a couple of patch points together. For example to parallel two load resistors.
#####
A little Fostex TT-15 tone generator for test signals when i am not near the bench.
#####
Mine is commercial, but a cable tester can be easily built. I can plug in a patch cord - like an RCA to RCA cord - and it tells me if the thing is open or shorted. I could do that with a meter easily enough, but with this I can yank and flex the cords to look for intermittants. Not so easy to do that with meter probes.
My little Whirlwind model is basic, but it allows not only say RCA to RCA cords to test, but you can also test RCA-1/4" or even XLR to one of those. It will also check phase reversal in an XLR cable.
#####
I don't use one of those little curve tracers, but I know a lot of techs who swear by them. You COULD spend over a thousand dollars for a Huntron Tracker or something, but for the price of a tiny transformer and a couple resistors stuffed in a little project box, you can make your own. Does require your scope be X-Y capable.
#####
If you are in pro audio, those plastic nuts on the Cliff jacks can be tough to grab with pliers. Go to the hardware and get a 15mm deep socket. Instant hand wrench for the nuts. (Deep sockets are sockets for a socket wrench that are maybe 65mm long. I don;t know if they have a different name elsewhere inthe world.)
#####
A magnifying glass. I have one with a stand - like those little stands that support a couple clips to hold things for soldering. I use it all day long. Set it there and hands free I can do close sodler work without tying up a hand.
#####
A 9v battery is a quick and reliable go/no-go tester for a speaker.
#####
A Dremel tool. Geez I use this thing all the time.
#####
One little thing I love is my "FybeRglass" brush eraser.
http://www.eraser.com/catalog.cgi?pt=&mode=details&category_id=&product_id=1222&
This thing is a little stiff brush originally made as an ink eraser for draftsmen, but it is a mild abrasive that is great on all manner of circuit board and other needs. They also come in brass bristles and stainless bristles. But the fiberglass is softer than the copper on a circuit board. You can scour away conformal coatings or even just shine away oxidation on exposed copper. Dirty edge connectors? No problem. Doesn't hurt the metal.
As the brush wears away, you advance it with the screw. When it wears out, you stick a new brush refill in it.
#####
A death cord. Simply an AC power cord with alligator clips on the end. Allows you to connect the mains to something. Good for checking loose power transformers or partial systems. For example I can power up a switching supply out of its host equipment
#####
A volume control in a box. Just a little project box with a pot in it. A couple jacks for in and out. Occasionally useful if I want to play with the level of something.
#####
A switched outlet for the unit under test on your bench is a common accessory, but i find having an ammeter on it adds to its value.
#####
A small DC power supply - good for checking relays and things.
enzo, i've made a couple of adapters for banana to Neutrik connectors which can come in handy with pro-audio too. even grabbed a couple of the dual purpose XLR/1/4" jacks out of scrapped power amps for "universal" adapters. those are an interesting molded jack to work with.
a function generator and scope makes for a "quick&dirty" ESR tester for caps. you can use 100Khz or 1Mhz as a test frequency, and the 50 ohm source impedance is easy to work with for figuring the ESR of a cap. for a quick ESR test, setting the F/G to 1 Mhz and 1Vp-p out, and setting the scope to 0.1V/div, any reading across a cap of more than 100mVp-p is a fail (that would be about 5 ohms ESR).
you can also test inductance and capacitance with a F/G and scope. if you have a cap and inductor of known value, you connect the known value component (let's say the cap) in series with the unknown component (in this case an inductor), apply the F/G across the series combination and monitor the F/G output with the scope and tune the F/G to where the output dips. that's the resonant frequency of the series L/C circuit. a little bit of math (the capacitor and the frequency are now the known values, solve for L) and you know the inductance.
a function generator and scope makes for a "quick&dirty" ESR tester for caps. you can use 100Khz or 1Mhz as a test frequency, and the 50 ohm source impedance is easy to work with for figuring the ESR of a cap. for a quick ESR test, setting the F/G to 1 Mhz and 1Vp-p out, and setting the scope to 0.1V/div, any reading across a cap of more than 100mVp-p is a fail (that would be about 5 ohms ESR).
you can also test inductance and capacitance with a F/G and scope. if you have a cap and inductor of known value, you connect the known value component (let's say the cap) in series with the unknown component (in this case an inductor), apply the F/G across the series combination and monitor the F/G output with the scope and tune the F/G to where the output dips. that's the resonant frequency of the series L/C circuit. a little bit of math (the capacitor and the frequency are now the known values, solve for L) and you know the inductance.
I made something similar but with an isolation transformer in the middle. I took two old halogen lamp transformers and made them into a single isolation transformer by taking them apart and reassembling one with two 120v coils. (I then made the two 12v coils and the other core into an electromagnet for other uses.) I put it into a large wall wart from some old PC speakers. The built in thermal breakers give it overload protection and it would buzz loudly when really overloaded.Enzo said:
"death cord"...... aka "widowmaker" and "suicide cord"....... it's known by those names for a reason 
although i'm sure most of us have needed to use one at one time or another. the isolation transformer isolates the voltage and current from ground, and if you brush up against a live circuit you will feel a tingle, but once you connect a scope ground, it is again referenced to ground and is as dangerous as not having an isolation transformer (actually it's more dangerous, just because of the perception that "it's isolated, so it's safe").
also, a banana plug with a wirewound 5W resistor between 10 and 100 ohms mounted on it is a good tool for discharging caps, just mount the resistor in such a way that you don't have to touch it while using the discharger, as it can get quite hot.
i used to use a tool for working on IBM computer monitors. it was a tool that fit into the slots on the top of the back of IBM monitors and popped free the plastic tabs that held the case together. the tool was made of stainless steel and was fashioned after the plastic ones that IBM supplied (which were easy to break). i still have the steel one in my toolbox, but i doubt i'll ever see an IBM 8514 VGA or 8515 SVGA monitor ever again....
although i'm sure most of us have needed to use one at one time or another. the isolation transformer isolates the voltage and current from ground, and if you brush up against a live circuit you will feel a tingle, but once you connect a scope ground, it is again referenced to ground and is as dangerous as not having an isolation transformer (actually it's more dangerous, just because of the perception that "it's isolated, so it's safe").also, a banana plug with a wirewound 5W resistor between 10 and 100 ohms mounted on it is a good tool for discharging caps, just mount the resistor in such a way that you don't have to touch it while using the discharger, as it can get quite hot.
i used to use a tool for working on IBM computer monitors. it was a tool that fit into the slots on the top of the back of IBM monitors and popped free the plastic tabs that held the case together. the tool was made of stainless steel and was fashioned after the plastic ones that IBM supplied (which were easy to break). i still have the steel one in my toolbox, but i doubt i'll ever see an IBM 8514 VGA or 8515 SVGA monitor ever again....
I avoid handling high voltage (and significant current) circuits with the power on when possible. I'm actually building a DC/DC converter that converts 10-16v to 180v (about 300-500w rating when finished) for a high efficiency UPS with support for alternative energy. When I need to make a change near the high voltage side, I turn off the bench power supply and discharge the capacitor before doing any work.unclejed613 said:"death cord"...... aka "widowmaker" and "suicide cord"....... it's known by those names for a reason
also, a banana plug with a wirewound 5W resistor between 10 and 100 ohms mounted on it is a good tool for discharging caps, just mount the resistor in such a way that you don't have to touch it while using the discharger, as it can get quite hot.
I would at least put a fuse or something in line with the cord in case the ends are accidentally shorted.
A 10 ohm resistor is too small for discharging most capacitors. It would result in a peak current of about 17A for a typical power supply capacitor, which is a lot. 100 ohms would be more reasonable, but still on the small side. I use either a 1.8k, 5w resistor (the kind with both leads on one end so I just hold it by the other end) or a small light bulb. (I prefer the bulb since it gives visual feedback.)
i used to use a 10 ohm on a production line without much problem except the ends of the banana plug would eventually get a bit scarred, and we were using them to discharge 15000uf/75V caps. there was still a small blue flash, and a barely audible snap, but it worked well without causing any melted wiring. the voltage on the caps was about +/-65V so the peak current was 6.5A. the banana plug pins were exactly the right distance apart to go from the rail fuse holder clips to a ground point that was near the fuses. but, no i wouldn't use it on SMPS primary caps....... they can be charged (depending on what type of input rectifier is used) at anywhere from 150 to 250V. that would definitely be a job for a 100ohm or more resistor. a 1k/5W wirewound would be a good choice.
i still use one from time to time........
i don't know if i mentioned this one before, but i keep all of the break-offs that come on new replacement boards. a lot of equipment these day has the front panel held on with plastic clips, but i only have 2 hands, and there may be as many as 10 clips holding a front panel on. i use the break-offs to wedge most of the clips open. the break-offs made out of really thin PC board material also come in handy for separating laptop, portable DVD, and monitor cases without leaving pry marks. some of the long skinny break-offs i've used to make "magic wands" for checking the bias and offset in Denon amps which have a small 3-pin connector in each channel. i hot glue a 3-pin cable with a matching connenctor to the end of a piece of break-off that's long enough to reach down to the main board and put alligator clips on the other end of the cable to connect to my meter leads.
i don't know if i mentioned this one before, but i keep all of the break-offs that come on new replacement boards. a lot of equipment these day has the front panel held on with plastic clips, but i only have 2 hands, and there may be as many as 10 clips holding a front panel on. i use the break-offs to wedge most of the clips open. the break-offs made out of really thin PC board material also come in handy for separating laptop, portable DVD, and monitor cases without leaving pry marks. some of the long skinny break-offs i've used to make "magic wands" for checking the bias and offset in Denon amps which have a small 3-pin connector in each channel. i hot glue a 3-pin cable with a matching connenctor to the end of a piece of break-off that's long enough to reach down to the main board and put alligator clips on the other end of the cable to connect to my meter leads.
I actually made a 120v test cord to test the idle current draw of some small power transformers I had. It has an inline fuse holder to protect against short circuits (currently with a 5A fuse installed), it is only about 1-2' in length so I can always clearly see the other end, and I always use it with either an isolation transformer or GFCI. It might sound like a lot of precautions but the engineering world really, *really* can't afford to lose a pretty engineer.
I use this record that I made once to test my equipment, since neighbors don't pay attention on it, but complain about any nice music. 
http://wavebourn.com/rain_helicopter.mp3
http://wavebourn.com/rain_helicopter.mp3
My favorite three cheap toos:
Finger - look for hot parts that shouldn't be.
Nose - For finding hot parts around HV or things too hot for finger (or for when finger is out-of-order with a bandage from finding said hot part).
Brain - "Wha ain'ts it werkin' nao?"
After that, a multimeter can't be beat
Cheers!
Finger - look for hot parts that shouldn't be.
Nose - For finding hot parts around HV or things too hot for finger (or for when finger is out-of-order with a bandage from finding said hot part).
Brain - "Wha ain'ts it werkin' nao?"
After that, a multimeter can't be beat
Cheers!
at work i usually use Robin Trower's "Too Rollin Stoned" to test speakers. since it's done by a 3 piece band, there are 3 distinct instruments for bass, midrange and treble, so if a driver in a speaker is blown, there's little doubt which one it is. plus, since i've been using it as test music for a very long time, i know the sound well enough to detect more subtle problems with speakers and amps. other 3-piece rock bands i like to use are Mahogany Rush, Grand Funk Railroad, and Jimi Hendrix Experience.......... i guess there isn't much doubt where my musical tastes lie....... 
I haven't seen this mentioned yet.
P3 P4400 125VAC Kill A Watt Electricity Usage Monitor - eBay (item 390227722320 end time Sep-18-10 01:34:11 PDT)
woops! http://www.diyaudio.com/forums/equipment-tools/114297-measuring-ac-amperage-multimeter.html
P3 P4400 125VAC Kill A Watt Electricity Usage Monitor - eBay (item 390227722320 end time Sep-18-10 01:34:11 PDT)
woops! http://www.diyaudio.com/forums/equipment-tools/114297-measuring-ac-amperage-multimeter.html
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slightly OT
It isn't really cheap, but this is working-out for me. I've gotten into collecting Tektronix 5000-series plugins. I'm about a year into my collecting "bug" and think these two units are a must for any serious audio nutt:
AA5001 - distortion analyzer
SG5010 - low distortion generator
and a TM5006A mainframe as well
Both those units can be automated over GPIB
The extra slot you can use for a little monitor scope like the SC502 on the agc'd function output from the AA5001
Grab another mainframe and collect some more cool plugins like a PS5010 lab supply, or maybe a DC5009 frequency counter. Don't consider a DC503A; not good for audio.
And it just keeps going all nice and compact, too.
It isn't really cheap, but this is working-out for me. I've gotten into collecting Tektronix 5000-series plugins. I'm about a year into my collecting "bug" and think these two units are a must for any serious audio nutt:
AA5001 - distortion analyzer
SG5010 - low distortion generator
and a TM5006A mainframe as well
Both those units can be automated over GPIB
The extra slot you can use for a little monitor scope like the SC502 on the agc'd function output from the AA5001
Grab another mainframe and collect some more cool plugins like a PS5010 lab supply, or maybe a DC5009 frequency counter. Don't consider a DC503A; not good for audio.
And it just keeps going
all nice and compact, too.
This one hasn't been mentioned and I use it all the time -
A fluke hand held IR thermometer. About AUS 120 (or US 119.9)
I use it all the time to measure temperatures of resistors, heatsinks and tubes.
Rob
I got one similar from RadShack last week for $20
I like ENZO's description of an AC test cord, a death cord.
I still use a "death cord" but after getting bit a few times, I decided to power my bench with a 20 amp line isolation transformer (electronics surplus store for $25) fed by a GFCI outlet. With this arrangement neither side of the isolated AC is tied to earth ground, so I have a degree of safety in case I accidentally touch the wrong wire.
On the bench, a favorite "cheap tool" is a B&K LCR meter. (It was purchased dirt cheap because it was non working, easy fix) It measures ESR at up to 100KHz which is sometimes critical for testing switching power supply capacitors.
Another favorite is a DPM milliohmmeter (bought used and repaired for under $50) which is conveniently battery powered. It can measure speaker wires with an accuracy to .00001 ohm. It can also inject up to 2 amps so the wires or circuit is tested under a real load condition. This meter has found its share of bad switches, crushed cords and loose connectors.
I also enjoy my AEMC megohmmeter because it too is battery powered and applies either 500 or 1,000 volts while testing. (These can still be purchased for $50 to $100) Some components test fine with a low voltage ohmmeter, but when you apply 500 volts or more, it shows how they change value under real world conditions. If I need lower voltage, I simply put the appropriate resistor in series with the resister under test to get the voltage needed.
Even though I have newer and "better"meters, I still use my 20+ year old Fluke 8050A meter on a regular basis. It is a 4.5 digit meter that measures conductance up to 100,000 Meg ohm, voltage measurements can be made in decibels with 16 different impedance settings, AC and DC current with a resolution of 0.01 uA. This was my 1st Fluke meter and it has been a favorite for years. I bought it used for $50 from a large company that decided it was cheaper to buy new meters every 3 years rather than having them calibrated. Hey, sometimes corporate decisions can benefit the DIYer.
I still use a "death cord" but after getting bit a few times, I decided to power my bench with a 20 amp line isolation transformer (electronics surplus store for $25) fed by a GFCI outlet. With this arrangement neither side of the isolated AC is tied to earth ground, so I have a degree of safety in case I accidentally touch the wrong wire.
On the bench, a favorite "cheap tool" is a B&K LCR meter. (It was purchased dirt cheap because it was non working, easy fix) It measures ESR at up to 100KHz which is sometimes critical for testing switching power supply capacitors.
Another favorite is a DPM milliohmmeter (bought used and repaired for under $50) which is conveniently battery powered. It can measure speaker wires with an accuracy to .00001 ohm. It can also inject up to 2 amps so the wires or circuit is tested under a real load condition. This meter has found its share of bad switches, crushed cords and loose connectors.
I also enjoy my AEMC megohmmeter because it too is battery powered and applies either 500 or 1,000 volts while testing. (These can still be purchased for $50 to $100) Some components test fine with a low voltage ohmmeter, but when you apply 500 volts or more, it shows how they change value under real world conditions. If I need lower voltage, I simply put the appropriate resistor in series with the resister under test to get the voltage needed.
Even though I have newer and "better"meters, I still use my 20+ year old Fluke 8050A meter on a regular basis. It is a 4.5 digit meter that measures conductance up to 100,000 Meg ohm, voltage measurements can be made in decibels with 16 different impedance settings, AC and DC current with a resolution of 0.01 uA. This was my 1st Fluke meter and it has been a favorite for years. I bought it used for $50 from a large company that decided it was cheaper to buy new meters every 3 years rather than having them calibrated. Hey, sometimes corporate decisions can benefit the DIYer.
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i have a test setup to measure the beta of output transistors. it consists of a 100uA current source to feed the base and a 30V power supply with 2A current limiting and an ammeter in the collector circuit. since the base current is known, the collector current divided by 100uA=beta. the current source doesn't care if the transistor is a regular bipolar or a darlington. i have been able to detect counterfeit Sanken darlington (2SD2390/B1560) devices with this test, since the fakes have very low beta and the real ones saturate at 100ua base current. the transistor is clamped to a heatsink with a squishy "gap-filler" sil-pad to conduct the heat.
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