Bi-toroid Transformer of Thane C. Heins

[BroMikey]

Dummy Load

Here is an audio amp dummy load resistor. Look at the criscross windings.

Says its non inductive. 1 ohm and 100watts $19




Mike

[BroMikey]

[QUOTE=Dog-One;265940can get away with it. Just make sure you don't have a ground path from your scope to your amp and that you connect the common on your probes to the exact same location.


[/QUOTE]


I was thinking the motor to a motor trick might keep me from the grounding problem. I am seeking isolation is any form easy to get. Do you think it will work?

Mike

[BroMikey]

Carbon

Hey Dave how about this 1ohm 5watt metal oxide film stuff?

Mike, I'm unsure of how you are going to use a differential probe to get an accurate current reading. I think we'd probably be more interested in current probes? Maybe I missed something..

[Dog-One]

Do you measure using a differential probe without issue?

Currently I'm not using diff probes--they're a must for something like a Stan Meyer VIC. Most of the ones I've seen have a battery inside them for power, at least my BK Precision ones do.


Without diff probes you have to have common for both probes on the negative side of the resistor and make sure you have no ground connected from your scope to house power. I'm really not too fond of this because one takes a chance on getting zapped or smoking the equipment. If you're careful and really think through how you have everything connected, you can get away with it. Just make sure you don't have a ground path from your scope to your amp and that you connect the common on your probes to the exact same location.


And Dave, a good current probe would be nice, but they're pricey too, usually more so than a decent differential probe. I tend to think if we use a small ohm carbon resistor, we should be in good shape. I'm using a 0.12 Ohm that seems good so far, at least it has been for low frequency.

[BroMikey]

Yeah

Don't use the phono input as this has a pre-amp on it. Use the line level (1 volt) inputs. You should be able to lower the output level on your signal generator to this level without issue.

If your amp is anything like mine, it will have an overload indicator on it that tells you when you are clipping the signal. Just reduce your input until this goes out then use your master volume control for how much power you want to inject into your SFT.

I agree, good coaching Dog-One


Do you measure using a differential probe without issue?

Mike

[BroMikey]

Probes

Mike, I'm unsure of how you are going to use a differential probe to get an accurate current reading. I think we'd probably be more interested in current probes? Maybe I missed something..

Ask Dog-One he thinks this can eliminate some ground and other measuring troubles. I don't think I have a probe like that anyway. I have a 1 ghz probe and some slower that come standard with the HP54100D.


Talk to me Dave. I need to hear more on the possibilities with current probe hookups and so on. Did you come up with a better circuit yet?

Maybe use a carbon resistor? Just a guess.


Mike

[BroMikey]

Package

Looks like the second cable hooks to the 1142 power control module. So this diff probe must not use batteries, i.e. it has its own power module. Does the 1142 power and control module come with the eBay package? You'll need that it looks like.

Yeah for $500
mike

[Web000x]

Mike, I'm unsure of how you are going to use a differential probe to get an accurate current reading. I think we'd probably be more interested in current probes? Maybe I missed something..

[Dog-One]

Hey Dog-One

I wanted to ask you a question about my amplifier.

I have an older (Like Brand New) version rack mount record player for LP records.

It has the standard inputs in the back but also the phone-O inputs that have a higher gain. Which one should I hook my generator to?

I can try them both to see if distortion is present.

Mike

Don't use the phono input as this has a pre-amp on it. Use the line level (1 volt) inputs. You should be able to lower the output level on your signal generator to this level without issue.

If your amp is anything like mine, it will have an overload indicator on it that tells you when you are clipping the signal. Just reduce your input until this goes out then use your master volume control for how much power you want to inject into your SFT.

[Dog-One]

Why does it have two cords? One terminates to the digital probe on the end and the other cord just stops? Do you know if this is a double probe?

Mike

Looks like the second cable hooks to the 1142 power control module. So this diff probe must not use batteries, i.e. it has its own power module. Does the 1142 power and control module come with the eBay package? You'll need that it looks like.

[BroMikey]

54100D Scope Book

This is wrong. I meant this is the book for the probe





Here is my scope.

http://www.trs-rentelco.com/Manual/AT_1141A_Manual.pdf

Mike

[BroMikey]

Guitar

I also have several larger amps for big speakers. 800 watt pyramid, 200 watt, 50 watt and more.

I want to keep them in one piece so i better use the small one first.

I have a sound setup for playing guitar and singing.

Mikey

[BroMikey]

If it will work, for $100 it's a bargain.

I'm sure with most HP gear you can check compatibility. I highly doubt there would be anything about it that makes it unusable.

Good find.

Coming At Dog-One

Here is the book on that probe and looking down the page I don't see a scope.

Can it still be used on a scope?

http://www.trs-rentelco.com/Manual/AT_1141A_Manual.pdf

Mike

[BroMikey]

2 Cords

If it will work, for $100 it's a bargain.

I'm sure with most HP gear you can check compatibility. I highly doubt there would be anything about it that makes it unusable.

Good find.

Why does it have two cords? One terminates to the digital probe on the end and the other cord just stops? Do you know if this is a double probe?

Mike

[BroMikey]

Question

If it will work, for $100 it's a bargain.

I'm sure with most HP gear you can check compatibility. I highly doubt there would be anything about it that makes it unusable.

Good find.

Hey Dog-One

I wanted to ask you a question about my amplifier.

I have an older (Like Brand New) version rack mount record player for LP records.

It has the standard inputs in the back but also the phone-O inputs that have a higher gain. Which one should I hook my generator to?

I can try them both to see if distortion is present.

Mike