I need a probe!
Moderators: pompeiisneaks, Colossal
Re: I need a probe!
exactly...
Re: I need a probe!
I think the Simpson VTVM is an entirely different animal.
Let me see if I can attach the pdf.
Let me see if I can attach the pdf.
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Re: I need a probe!
OH - haven't seen one of those in ages.... 
Nice instrument!
If you look closely at the schematic, you'll see that the standard probe is nothing but a 1M resistor in series when measuring DC, whcih is bypassed with a switch fro measuring AC/ohms....
As for teh HP,- this is a 'function' generator with DC offset capability. This means that the signal output is DC coupled and will NOT like any substantial reverse DC input coming from the feed point. Use a big honkin' blocking cap!
Had one of those on my lab bench back in the 80s..... nice little generator!
Nice instrument!If you look closely at the schematic, you'll see that the standard probe is nothing but a 1M resistor in series when measuring DC, whcih is bypassed with a switch fro measuring AC/ohms....
As for teh HP,- this is a 'function' generator with DC offset capability. This means that the signal output is DC coupled and will NOT like any substantial reverse DC input coming from the feed point. Use a big honkin' blocking cap!
Had one of those on my lab bench back in the 80s..... nice little generator!
Re: I need a probe!
Someday I'll get smart and figure out why this old equipment is being tossed to the curb (not literally, but close).
The Tek 466 storage scope works, and was a gift, free.
The Simpson VTVM was $5 and looked too cool to pass up.
I have several decade boxes that cost nearly nothing.
Loaded with .5% resistors and switches heavy enough to use as speaker impedance selectors.
One Eiko capacitance sub box, also stupid cheap.
A couple of isolation transformers...yes, cheap.
I already have a Powerstat variac and a light bulb limiter that I've been using for years.
And now this function generator tugged on my leg...and I had to have it.
It's the most expensive piece so far at $50.00.
The Tek 466 storage scope works, and was a gift, free.
The Simpson VTVM was $5 and looked too cool to pass up.
I have several decade boxes that cost nearly nothing.
Loaded with .5% resistors and switches heavy enough to use as speaker impedance selectors.
One Eiko capacitance sub box, also stupid cheap.
A couple of isolation transformers...yes, cheap.
I already have a Powerstat variac and a light bulb limiter that I've been using for years.
And now this function generator tugged on my leg...and I had to have it.
It's the most expensive piece so far at $50.00.
Re: I need a probe!
Yes I've been building and repairing radios, stereos, and amps for years using nothing but a giant hammer and some chisels...but seriously I know NOTHING about this equipment.Aurora wrote:OH - haven't seen one of those in ages....
If you look closely at the schematic, you'll see that the standard probe is nothing but a 1M resistor in series when measuring DC, whcih is bypassed with a switch fro measuring AC/ohms....
As for teh HP,- this is a 'function' generator with DC offset capability. This means that the signal output is DC coupled and will NOT like any substantial reverse DC input coming from the feed point. Use a big honkin' blocking cap!
Had one of those on my lab bench back in the 80s..... nice little generator!
I use meters, a portable radio to inject signals, and such.
You're going to have to draw some pictures for me...
I'm really a caveman in a modern world here.
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Reeltarded
- Posts: 10144
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Re: I need a probe!
Function generator?! I AM ONE!
For instance: (yells to woman) "Make me a sandwich!"
Easy!
DC offset.. you know.. over to one side or above..
For instance: (yells to woman) "Make me a sandwich!"
Easy!
DC offset.. you know.. over to one side or above..
Re: I need a probe!
True, but this HP ain't sitting here asking me for sammiches.Reeltarded wrote:Function generator?! I AM ONE!
For instance: (yells to woman) "Make me a sandwich!"
Easy!
DC offset.. you know.. over to one side or above..
Really, I did think of you first Miles.
But this little guy looked so cute tugging on my pants leg...
OK, so HOW big of a cap should I use to block reverse DC with?
Can't imagine it has to be very high for the voltage rating.
Re: I need a probe!
Here's a picture of my unit. It uses BNC connectors terminating in alligator clips. The panel mount BNC connectors are on the left side of the unit below the three dials.
HTH
HTH
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Re: I need a probe!
Well, it is actually a very good little generator, and probably well worth the price....
but take care- it is full of parts of which more than several are now unobtanium.......
Over time , most instruments do slide more or less out of calibration. For serious professional use, calibration of an advanced professional lab setup cost a lot more than an arm and a couple of legs these days.
Things like decade boxes and such, which are very nice for practical experiment with circuits, are now replaced by software simulators and PCs. In fact , a lot of greenhorn young engineers these days just cannot manage practical work. They will do almost ANYTHING that can be simulated on a computer, but teaching these youngsters how to work with real tools and instruments is a real chore some of them just don't master anymore...
but take care- it is full of parts of which more than several are now unobtanium.......
Over time , most instruments do slide more or less out of calibration. For serious professional use, calibration of an advanced professional lab setup cost a lot more than an arm and a couple of legs these days.
Things like decade boxes and such, which are very nice for practical experiment with circuits, are now replaced by software simulators and PCs. In fact , a lot of greenhorn young engineers these days just cannot manage practical work. They will do almost ANYTHING that can be simulated on a computer, but teaching these youngsters how to work with real tools and instruments is a real chore some of them just don't master anymore...
Re: I need a probe!
Thanks Nick, I think it's clear now.
Aurora, the Tek was calibrated shortly before I got it, and I just have not used it.
I figured for the signal generator...really I'm just going to be pushing a standard 1K wave for the most part, so it should get me close...right?
I forgot, something else I've been using for several years is a Hickok 6000A tube tester that was gifted to me.
I checked it with known values from other calibrated testers, and keep those for reference.
I won't "certify" anyone's tubes with it, but it has proven to be a great tool.
Although I'm showing myself to be completely ignorant here, I have been using homebrew workarounds for so many years that I have no problem learning.
That demonstrates critical thinking skills...something that hopefully leads to common sense.
"Which we could use more of".
Aurora, the Tek was calibrated shortly before I got it, and I just have not used it.
I figured for the signal generator...really I'm just going to be pushing a standard 1K wave for the most part, so it should get me close...right?
I forgot, something else I've been using for several years is a Hickok 6000A tube tester that was gifted to me.
I checked it with known values from other calibrated testers, and keep those for reference.
I won't "certify" anyone's tubes with it, but it has proven to be a great tool.
Although I'm showing myself to be completely ignorant here, I have been using homebrew workarounds for so many years that I have no problem learning.
That demonstrates critical thinking skills...something that hopefully leads to common sense.
"Which we could use more of".
Re: I need a probe!
Rat Shack had the 12' BNC 50 ohm lead, plus I bought a couple of BNC to RCA adapters.
We're in business!
Hooked up the generator to an amp and it made appropriate noises at 1K.
Also connected to the Tek scope and it made pretty pictures.
Got caught up in watching YT vids about Jim Williams as I was looking for info on using the scope.
RIP Jim.
We're in business!
Hooked up the generator to an amp and it made appropriate noises at 1K.
Also connected to the Tek scope and it made pretty pictures.
Got caught up in watching YT vids about Jim Williams as I was looking for info on using the scope.
RIP Jim.
Re: I need a probe!
Heh, none of this was anywhere near as difficult as I thought.
Started playing around with the function generator and the scope.
Now I'm in dual trace heaven inside some amps.
Turns out to have been a GREAT troubleshooting tool on a flaky gain stage on one that had me scratching for an answer.
It told me things I couldn't possibly hear.
Thx 4 all T hlp!
Started playing around with the function generator and the scope.
Now I'm in dual trace heaven inside some amps.
Turns out to have been a GREAT troubleshooting tool on a flaky gain stage on one that had me scratching for an answer.
It told me things I couldn't possibly hear.
Thx 4 all T hlp!
Re: I need a probe!
Wait, said something about a cap to block potential DC into the function generator.
What size, type and rating should I use?
What size, type and rating should I use?
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Super_Reverb
- Posts: 188
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- Location: Indianapolis, USA
Re: I need a probe!
I made probes for my scope from small diameter coax, bnc connector and two EZ hooks. You don''t really need an expensive probe. Bandwidth on a guitar amp is ~10kHz. If you'd rather use a manufactured probe, they are cheap on ebay. Be sure you order a RoHS probe, cuz we all know how insanely toxic tin/lead solder is... 
Re: I need a probe!
Thanks SR.Aurora wrote: This means that the signal output is DC coupled and will NOT like any substantial reverse DC input coming from the feed point. Use a big honkin' blocking cap!
I bought the BNC's.
My big question goes to Aurora's statement above.
What size cap?
What type?
What voltage?