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Re: USB interface for the DPO / P7001

 

On Thu, Dec 2, 2021 at 10:56 AM, Harvey White wrote:


Couple things on USB that might help.

You can easily buy a TTL to USB converter.? Takes TTL level (as from
uart/usart) signals, either 3.3 or 5.0 volts, and translates them to a
USB signal.? That USB signal, when plugged into a PC, enumerates as a
serial port.? You set the baudrate at the terminal to match the TTL
baudrate.

In a number of microprocessor boards (my experience is with the ST-MICRO
boards), the USB chip on the board used for programming also has a
virtual terminal function (at the same time as debugging).? The USB chip
is hardwired to a USART output on the processor.? If you don't use those
pins for something else, and don't disconnect them, you can initialize
that particular USART on the processor and use it to communicate through
the debugging cable.? Your debugging system runs an instance of a
terminal program.

In addition, if you enable the fprint functions in your system and
direct them to the USB usart channel, you can get ongoing outputs from
the processor to the computer for monitoring a process.? You could also
use the console in and out functions, but those may need to be
redirected in your program.

Really easier than you might think.

As to emulating a true HID device, I haven't tried that, haven't needed
to, but I suspect with the right drivers, emulating an HID device
(mouse, etc) might be easy enough.

Harvey


On 12/2/2021 12:07 PM, Chris Wilkson via groups.io wrote:
This is fantastic work, Holger!

I have a disembodied P7001 that I keep meaning to add to a 7704 so I can
play with it. Or, finally accept that I will never get to it and pass the
p7001 to a new owner.
Your project tilts my internal debate toward "keep it". :)

Quick question on Teensy: Can it be configured as a USB HID host?
I have many homebrew projects that would benefit from a USB keyboard-to-TTL
converter but I'm honestly intimidated by USB complexity so I haven't done
much research on USB hosts.





Hi Harvey,

My need is actually in the other direction. There is no PC involved anywhere.

There are a million ways to connect a random electronics project to a PC through USB, typically using an FTDI IC with a virtual com port in Windows. Which is the way you described. Or using a development board from an MCU manufacturer or something in the Arduino ecosystem. But cursory searches turn up little info on preexisting solutions for connecting commercial USB devices (keyboard, mouse, usb stick, whatever) to a random electronics project.

Here's an example of what I want to do. I have a working USB keyboard (standard COTS device) that I want to interface to a vintage CPU. Say a 6502 for example. Or even to a discrete TTL design. So I need a USB *host* that can talk to the keyboard and spit out raw data on the other side in serial or preferably parallel format. I went down the PS2 -> TTL route years and years ago. It was fairly trivial. But USB host implementation is a whole different animal.

Best,
Chris
Re: TG501 2ns & 1ns operation

 

I just did a few experiments using a 7103 (1 Ghz) scope, in which I had a 7A29 (1Ghz) and a 7A19 (500 Mhz).

Using a TG501, and having calibrated each with a PG506, you get (roughly) the following observations.? These are observations only, though.

With the 2 ns marker, going between the 7A29 (say 800 mv p/p) shows you 700 mv p/p on a 7A19.

The 1 ns timing waveform is less than the 2 ns waveform on the 7A29.? Call the 1 ns timing waveform about 300 mv p/p.

with the 1 ns output observed, turning on the 2 ns output drops the 1 ns output by about 50% or so.? It doesn't stop it.? Turning on the 5 ns output will kill the 1 ns output.

I've found no difference in waveshape between the 1 ns and 2 ns outputs regardless of pushbutton, when both are present.

I'm going to guess that the bandwidth of a 7A19 and a 7103 is the same as a 7934 and a 7A29, so this should be meaningful for you.

I'd say that while your 1 ns output is a bit low (perhaps), remember that is wasn't really intended to be anything but a source of timing markers.

I'd also suggest that the 1 ns output is possibly visible on your equipment, but at a very reduced amplitude.

Harvey

On 12/2/2021 12:17 PM, Dave Peterson via groups.io wrote:
Hi all,

I've been working on rehabbing a TG501. After replacing the shorted Tantalum filter caps on the 15v supply the device has operated pretty well. I've been learning the operation, circuits, and tuning of it without too much difficulty. I've gotten the timing marks synced with a Leo Bodnar GPSDO and, despite not having the OPT1 1MHz oscillator, can achieve a very stable output. That is, almost no drift relative to the GPSDO at 1MHz over long periods of time. Nice output levels too.

A remaining issue I'm having leads me to wonder how the 1ns and 2ns circuits are intended to work. First, I understand 1ns is pretty fast for the equipment I have on hand, but I do have a 7934 with 7B92A time base, and 7A29 vertical amplifiers. It's all in less than ideal condition, but functioning well enough for me to observe the 1ns sine wave. Albeit at a weak level. Is this the 7934 BW limit, or the TG501? Undetermined yet.

But the 2ns output is plenty strong - up to 1.5v p2p. Adjustment of C515 between 1ns and 2ns levels has me turning it down to about 800mv p2p. But still I cannot get anything more than about 40mv p2p on the 1ns output (see above - is it the BW limit of the 7934, or the TG501?).

In working on these outputs I've had them both on the 7934 through both the left and right vertical slots, both going through 7A29s. Switching between the 1ns and 2ns push buttons results in both outputs present (2ns on MARKER OUT, 1ns on 1NS ONLY), but when in 1ns mode the 2ns output drops from 800mv p2p (or whatever I've set it to) to about 40mv p2p. The 1ns sine wave output remains fairly consistent at about 40mv p2p. It looks pretty good - a good sine wave, and the level does change a few mV between 1ns and 2ns settings. The 2ns waveform however, goes from looking beautiful in 2ns mode to ugly (not a clean sine waveform) in 1ns mode.

I'm trying to understand how this is happening. Studying the A2 Multiplier Board schematic <4>, I don't see what the 1ns/2ns push buttons even do to affect the 1ns/2ns circuit operation. It looks like these push buttons are tied together at the input of NOR gate U450C. That having either pushed in enables this gate to pass the 100MHz oscillator into the 10ns Amplifier of Q484/Q486. And it also looks like these push buttons both operate/enable K450, and should result in both 2ns and 1ns outputs to be at their respective output BNCs: MARKER OUT and 1NS ONLY. How is selecting 1ns causing the MARKER OUT output to drop?

I'm suspicious of CR515, but given I don't even see how the 10ns Amplifier output should change at all, that seems to be ignorant grasping. Is there something about the input to U450C I'm not understanding? It seems the 1ns and 2ns outputs should always be present, and the 1ns and 2ns push buttons seem redundant - there should just be one button and both outputs?

I'm perfectly comfortable recognizing the 1ns output level to be BW limited by my setup. It makes tuning C515 guesswork, but I can live with that. If I can't even discern the 1ns output reliably with the equipment I have, I don't actually have much (any?) need for it. But it bothers me that that 2ns is so adversely affected. And that I can't understand why the circuit behaves this way. So any insights are greatly appreciated.

Thanks,
Dave
Re: USB interface for the DPO / P7001

 

Couple things on USB that might help.

You can easily buy a TTL to USB converter.? Takes TTL level (as from uart/usart) signals, either 3.3 or 5.0 volts, and translates them to a USB signal.? That USB signal, when plugged into a PC, enumerates as a serial port.? You set the baudrate at the terminal to match the TTL baudrate.

In a number of microprocessor boards (my experience is with the ST-MICRO boards), the USB chip on the board used for programming also has a virtual terminal function (at the same time as debugging).? The USB chip is hardwired to a USART output on the processor.? If you don't use those pins for something else, and don't disconnect them, you can initialize that particular USART on the processor and use it to communicate through the debugging cable.? Your debugging system runs an instance of a terminal program.

In addition, if you enable the fprint functions in your system and direct them to the USB usart channel, you can get ongoing outputs from the processor to the computer for monitoring a process.? You could also use the console in and out functions, but those may need to be redirected in your program.

Really easier than you might think.

As to emulating a true HID device, I haven't tried that, haven't needed to, but I suspect with the right drivers, emulating an HID device (mouse, etc) might be easy enough.

Harvey

On 12/2/2021 12:07 PM, Chris Wilkson via groups.io wrote:
This is fantastic work, Holger!

I have a disembodied P7001 that I keep meaning to add to a 7704 so I can play with it. Or, finally accept that I will never get to it and pass the p7001 to a new owner.
Your project tilts my internal debate toward "keep it". :)

Quick question on Teensy: Can it be configured as a USB HID host?
I have many homebrew projects that would benefit from a USB keyboard-to-TTL converter but I'm honestly intimidated by USB complexity so I haven't done much research on USB hosts.
Re: TG501 2ns & 1ns operation

 

On Thu, Dec 2, 2021 at 06:17 PM, Dave Peterson wrote:


A remaining issue I'm having leads me to wonder how the 1ns and 2ns circuits
are intended to work. First, I understand 1ns is pretty fast for the equipment
I have on hand, but I do have a 7934 with 7B92A time base, and 7A29 vertical
amplifiers. It's all in less than ideal condition, but functioning well enough
for me to observe the 1ns sine wave. Albeit at a weak level. Is this the 7934
BW limit, or the TG501? Undetermined yet.

The 1ns sine wave output remains fairly consistent at about 40mv p2p.
FYI:

Both my TG501's show the following at 1ns, using ordinary RG58C/U cable:
In 7854/7S11/7T11A/S-4 (BW ca. 14GHz): 320mVpp
in 7904 with 7A29: 200mVpp

Spec for the TG501 is >= 200 mVpp @ 1ns


It looks pretty good - a good sine wave
Because the "pulse" @ 1ns is fast for the equipment (including the 1ns "source" itself!), you can't really expect to see
anything else than a sinewave-like shape, because that would indicate the presence of harmonics, which of course
are outside the equipment's BW limits.
Even using the 14GHz 'scope, the 1ns signal looks like a pretty good sinewave, because of the properties of the TG501.

Raymond
Re: USB interface for the DPO / P7001

 

Hi Chris!

Yes, at least the Teensy 4.1 supports that mode. You can even use one of the USB ports as an HID host for incoming data and the other USB port can emulate a keybord for sending data to another HID host.

Holger
Re: 1502 TDR RECORD functions

 

You didn't have it in a conduit?? That cut could be spectacular if the line were energized!? ? ? ?Jim Ford?Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: fiftythreebuick <spitfiremarkiv@...> Date: 12/2/21 10:00 AM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] 1502 TDR RECORD functions I've also use a TDR to find where the yard men cut the romex going to our front lamp post as well.? Such a useful tool!? :-)Tom
Re: 1502 TDR RECORD functions

 

Chris, you NEED one! :-)

The first time I tried this was many years ago and out of a string of 100 bulbs, it found each of 13 open bulbs! Oh, that that time I was actually using a 1S2 in a 556 mainframe. Had to bring the lights to the scope that time... <laughing>

Tom
Re: 1502 TDR RECORD functions

 

Hi Paul-

These are incandescent but LEDs should work fine too. One nice thing is that the display reacts so quickly, so that when you move the string around you can spot intermittents, even if they're quite brief.

Tom
Re: 1502 TDR RECORD functions

 

I've also use a TDR to find where the yard men cut the romex going to our front lamp post as well. Such a useful tool! :-)

Tom
Re: TG501 2ns & 1ns operation

 

Hi Dave,
It looks like the 7932 is a 500 Mhz scope so you be well past 3db down at 1ns time marks. To tune these in the lab I have to scale up to a DSA602A with a 11A72. This gets me right to 1Ghz. The fact that 7932 can trigger is impressive and that trace is viewable is also impressive as the frame is being pushed to double its bandwidth. With this setup wave shape can be inferred but amplitude can not. I would not trust anything "calibration" related out this far. But this also depends on your needs.

Zen

-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Dave Peterson via groups.io
Sent: Thursday, December 2, 2021 12:17 PM
To: [email protected]
Subject: [TekScopes] TG501 2ns & 1ns operation

Hi all,

I've been working on rehabbing a TG501. After replacing the shorted Tantalum filter caps on the 15v supply the device has operated pretty well. I've been learning the operation, circuits, and tuning of it without too much difficulty. I've gotten the timing marks synced with a Leo Bodnar GPSDO and, despite not having the OPT1 1MHz oscillator, can achieve a very stable output. That is, almost no drift relative to the GPSDO at 1MHz over long periods of time. Nice output levels too.

A remaining issue I'm having leads me to wonder how the 1ns and 2ns circuits are intended to work. First, I understand 1ns is pretty fast for the equipment I have on hand, but I do have a 7934 with 7B92A time base, and 7A29 vertical amplifiers. It's all in less than ideal condition, but functioning well enough for me to observe the 1ns sine wave. Albeit at a weak level. Is this the 7934 BW limit, or the TG501? Undetermined yet.

But the 2ns output is plenty strong - up to 1.5v p2p. Adjustment of C515 between 1ns and 2ns levels has me turning it down to about 800mv p2p. But still I cannot get anything more than about 40mv p2p on the 1ns output (see above - is it the BW limit of the 7934, or the TG501?).

In working on these outputs I've had them both on the 7934 through both the left and right vertical slots, both going through 7A29s. Switching between the 1ns and 2ns push buttons results in both outputs present (2ns on MARKER OUT, 1ns on 1NS ONLY), but when in 1ns mode the 2ns output drops from 800mv p2p (or whatever I've set it to) to about 40mv p2p. The 1ns sine wave output remains fairly consistent at about 40mv p2p. It looks pretty good - a good sine wave, and the level does change a few mV between 1ns and 2ns settings. The 2ns waveform however, goes from looking beautiful in 2ns mode to ugly (not a clean sine waveform) in 1ns mode.

I'm trying to understand how this is happening. Studying the A2 Multiplier Board schematic <4>, I don't see what the 1ns/2ns push buttons even do to affect the 1ns/2ns circuit operation. It looks like these push buttons are tied together at the input of NOR gate U450C. That having either pushed in enables this gate to pass the 100MHz oscillator into the 10ns Amplifier of Q484/Q486. And it also looks like these push buttons both operate/enable K450, and should result in both 2ns and 1ns outputs to be at their respective output BNCs: MARKER OUT and 1NS ONLY. How is selecting 1ns causing the MARKER OUT output to drop?

I'm suspicious of CR515, but given I don't even see how the 10ns Amplifier output should change at all, that seems to be ignorant grasping. Is there something about the input to U450C I'm not understanding? It seems the 1ns and 2ns outputs should always be present, and the 1ns and 2ns push buttons seem redundant - there should just be one button and both outputs?

I'm perfectly comfortable recognizing the 1ns output level to be BW limited by my setup. It makes tuning C515 guesswork, but I can live with that. If I can't even discern the 1ns output reliably with the equipment I have, I don't actually have much (any?) need for it. But it bothers me that that 2ns is so adversely affected. And that I can't understand why the circuit behaves this way. So any insights are greatly appreciated.

Thanks,
Dave
TG501 2ns & 1ns operation

 

Hi all,

I've been working on rehabbing a TG501. After replacing the shorted Tantalum filter caps on the 15v supply the device has operated pretty well. I've been learning the operation, circuits, and tuning of it without too much difficulty. I've gotten the timing marks synced with a Leo Bodnar GPSDO and, despite not having the OPT1 1MHz oscillator, can achieve a very stable output. That is, almost no drift relative to the GPSDO at 1MHz over long periods of time. Nice output levels too.

A remaining issue I'm having leads me to wonder how the 1ns and 2ns circuits are intended to work. First, I understand 1ns is pretty fast for the equipment I have on hand, but I do have a 7934 with 7B92A time base, and 7A29 vertical amplifiers. It's all in less than ideal condition, but functioning well enough for me to observe the 1ns sine wave. Albeit at a weak level. Is this the 7934 BW limit, or the TG501? Undetermined yet.

But the 2ns output is plenty strong - up to 1.5v p2p. Adjustment of C515 between 1ns and 2ns levels has me turning it down to about 800mv p2p. But still I cannot get anything more than about 40mv p2p on the 1ns output (see above - is it the BW limit of the 7934, or the TG501?).

In working on these outputs I've had them both on the 7934 through both the left and right vertical slots, both going through 7A29s. Switching between the 1ns and 2ns push buttons results in both outputs present (2ns on MARKER OUT, 1ns on 1NS ONLY), but when in 1ns mode the 2ns output drops from 800mv p2p (or whatever I've set it to) to about 40mv p2p. The 1ns sine wave output remains fairly consistent at about 40mv p2p. It looks pretty good - a good sine wave, and the level does change a few mV between 1ns and 2ns settings. The 2ns waveform however, goes from looking beautiful in 2ns mode to ugly (not a clean sine waveform) in 1ns mode.

I'm trying to understand how this is happening. Studying the A2 Multiplier Board schematic <4>, I don't see what the 1ns/2ns push buttons even do to affect the 1ns/2ns circuit operation. It looks like these push buttons are tied together at the input of NOR gate U450C. That having either pushed in enables this gate to pass the 100MHz oscillator into the 10ns Amplifier of Q484/Q486. And it also looks like these push buttons both operate/enable K450, and should result in both 2ns and 1ns outputs to be at their respective output BNCs: MARKER OUT and 1NS ONLY. How is selecting 1ns causing the MARKER OUT output to drop?

I'm suspicious of CR515, but given I don't even see how the 10ns Amplifier output should change at all, that seems to be ignorant grasping. Is there something about the input to U450C I'm not understanding? It seems the 1ns and 2ns outputs should always be present, and the 1ns and 2ns push buttons seem redundant - there should just be one button and both outputs?

I'm perfectly comfortable recognizing the 1ns output level to be BW limited by my setup. It makes tuning C515 guesswork, but I can live with that. If I can't even discern the 1ns output reliably with the equipment I have, I don't actually have much (any?) need for it. But it bothers me that that 2ns is so adversely affected. And that I can't understand why the circuit behaves this way. So any insights are greatly appreciated.

Thanks,
Dave
Re: USB interface for the DPO / P7001

 

This is fantastic work, Holger!

I have a disembodied P7001 that I keep meaning to add to a 7704 so I can play with it. Or, finally accept that I will never get to it and pass the p7001 to a new owner.
Your project tilts my internal debate toward "keep it". :)

Quick question on Teensy: Can it be configured as a USB HID host?
I have many homebrew projects that would benefit from a USB keyboard-to-TTL converter but I'm honestly intimidated by USB complexity so I haven't done much research on USB hosts.
Re: Help required finding a Tek 466 power rail short

 

On Wed, Dec 1, 2021 at 9:57 PM James55 <james_55@...> wrote:

Did try with a PSU on that rail but couldn't feel any heat, although the
voltage did immediately drop to zero.
If you have a high-resolution DMM, you can play a game of warmer/colder by
measuring the voltage across components or traces. If you pump 1A in,
you'll have a voltage delta of 1V per Ohm. The traces carrying the current
to the shorted component will make like resistors, and the voltage will be
lowest next to the short. With a 6 1/2 digit DMM, especially if you zero on
the input voltage you can get really, really close to the short pretty
quickly.
Re: Tektronix 1900 NTSC test signal generator - basically dead

 

On 2021-12-01 9:53 p.m., toby@... wrote:
Hi,
In the project of repairing something else (634 monitor) I rolled the ebay die on a local* 1900 test signal generator but definitely did not win, found it basically non-working (LEDs light arbitrarily, front panel non responsive).
The LV rails are within reasonable limits excepting about 1V ac ripple on +15v and about 0.3V ac ripple on the +5. Will look at replacing some of the huge pre-regulator filter caps before giving up...


--T

Service manuals are expensive on ebay for this unit and I'm not highly motivated to fix it. Anyone need a parts mule? And secondly, anyone interested in parting with a _working_ NTSC test signal generator?
--Toby
* Toronto Canada
Re: 1502 TDR RECORD functions

 

I have to ask how you handle the transition from coax to the Xmas lights? And how you interpret the results.

A picture of two may be worth a 1000 words.
D.

-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Glydeck via groups.io
Sent: 02 December 2021 05:23
To: [email protected]
Subject: Re: [TekScopes] 1502 TDR RECORD functions

Good question. I don¡¯t think it matters. An interruption in the transmission line does not care if it¡¯s a LED or a bulb. I¡¯m so trying this on some recalcitrant light strings.

Glydeck KD6NEW
On Dec 1, 2021, at 6:32 PM, Paul Amaranth <paul@...> wrote:

?Was that incandescant or LED lights?

I have an entire bin full of LED strings that are dead and that might
be worth a try.

Paul

On Wed, Dec 01, 2021 at 01:51:54PM -0800, fiftythreebuick wrote:
Tom, the 1502 is one of the most useful instruments around!

I just finished finding the fault in a long string of Christmas lights with mine! :-) Definitely something essential to have around...

Tom
--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@... | Unix/Linux - We don't do windows
Re: 1502 TDR RECORD functions

 

Hmmmm.... I? wonder if the wife will let me buy an 11800 series scope and an SD-24 for finding bum bulbs?? I suppose it would only work for strings and not net lights.? ? Jim Ford?Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: "ChrisBeee via groups.io" <chrisbeee@...> Date: 12/1/21 9:24 PM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] 1502 TDR RECORD functions Tom, you definitely made my day with this very convincing excuse for having one of those instruments!! =DChrisOn Wed, Dec? 1, 2021 at 10:51 PM, fiftythreebuick wrote:>> Tom, the 1502 is one of the most useful instruments around!> > I just finished finding the fault in a long string of Christmas lights with> mine!? :-)? Definitely something essential to have around...? > > Tom>
Re: 1502 TDR RECORD functions

 

Tom,
you definitely made my day with this very convincing excuse for having one of those instruments!! =D
Chris

On Wed, Dec 1, 2021 at 10:51 PM, fiftythreebuick wrote:


Tom, the 1502 is one of the most useful instruments around!

I just finished finding the fault in a long string of Christmas lights with
mine! :-) Definitely something essential to have around...

Tom
Re: 1502 TDR RECORD functions

 

Good question. I don¡¯t think it matters. An interruption in the transmission line does not care if it¡¯s a LED or a bulb. I¡¯m so trying this on some recalcitrant light strings.

Glydeck KD6NEW

On Dec 1, 2021, at 6:32 PM, Paul Amaranth <paul@...> wrote:

?Was that incandescant or LED lights?

I have an entire bin full of LED strings that are dead and that might
be worth a try.

Paul

On Wed, Dec 01, 2021 at 01:51:54PM -0800, fiftythreebuick wrote:
Tom, the 1502 is one of the most useful instruments around!

I just finished finding the fault in a long string of Christmas lights with mine! :-) Definitely something essential to have around...

Tom
--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@... | Unix/Linux - We don't do windows
Re: Help required finding a Tek 466 power rail short

 

Hi Siggi and thanks for the reply.

Did try with a PSU on that rail but couldn't feel any heat, although the voltage did immediately drop to zero.

I must have motivated myself after making the post for I was able to find another shorted capacitor and also to identify the shorted rail as the 5 volt one. Following that I disconnected one of the ac wires supplying the 5v bridge rectifier and switched it on... only for the Op-Amp U1762 to promptly explode - Doh!

I'll replace that and the shorted caps tomorrow, make a dimbulb test rig before focusing on the 5v rail, and for sure I'll try the IPA trick too.

My suspicion is that the failed component lies further along inside the scope and the manual isn't the clearest as to where I might be needing to look.

It is in the 'Files' section if anyone is interested;

/g/TekScopes/filessearch?p=name%2C%2C%2C50%2C1%2C0%2C0&q=tek+466
Tektronix 1900 NTSC test signal generator - basically dead

 

Hi,

In the project of repairing something else (634 monitor) I rolled the ebay die on a local* 1900 test signal generator but definitely did not win, found it basically non-working (LEDs light arbitrarily, front panel non responsive).

Service manuals are expensive on ebay for this unit and I'm not highly motivated to fix it. Anyone need a parts mule? And secondly, anyone interested in parting with a _working_ NTSC test signal generator?

--Toby

* Toronto Canada
20421 - 20440 of 208536