# I don't have an oscilloscope

#### Arjune

Joined Jan 6, 2018
131
This is my 1hz pulser. Will lo state reach close to zero (I want that) volts at output? I don't have an oscilloscope to see the waveform. I know the hi state is 5.3v. I am able to clock a cmos modulus 60 counter okay with it. Can it clock TTL.

Last edited by a moderator:

Joined Mar 10, 2018
4,057
If you do not have a scope here is a low speed freebee -

audio range scope, spectrum analyzer, and function generator all using your
PC sound card. It may not be fast enough to handle the character LCD interface
however.

https://www.zeitnitz.eu/scope_en

http://www.zelscope.com/

http://www.ledametrix.com/oscope/

But first build a simple circuit to protect sound card inputs so you do not
ruin from transients, overvoltage. Google "protect sound card input".

For example http://makezine.com/projects/sound-card-oscilloscope/

A real inexpensive Logic Analyzer/pc combo can be had with this -

https://www.ebay.com/itm/USB-Logic-...h=item33f2ef28ec:g:NNoAAOSwjXVaoiyH:rk:4f:0

There are many vendors of this on ebay.

Sound card impedance bridge -

http://www.marucchi.it/ZRLC_web/ZRLC/Steber_An_LMS_Impedance_Bridge.pdf

http://www.sillanumsoft.org/ZRLC.htm

Regards, Dana.

#### spinnaker

Joined Oct 29, 2009
7,835
If you do not have a scope here is a low speed freebee -

audio range scope, spectrum analyzer, and function generator all using your
PC sound card. It may not be fast enough to handle the character LCD interface
however.

https://www.zeitnitz.eu/scope_en

http://www.zelscope.com/

http://www.ledametrix.com/oscope/

But first build a simple circuit to protect sound card inputs so you do not
ruin from transients, overvoltage. Google "protect sound card input".

For example http://makezine.com/projects/sound-card-oscilloscope/

A real inexpensive Logic Analyzer/pc combo can be had with this -

https://www.ebay.com/itm/USB-Logic-...h=item33f2ef28ec:g:NNoAAOSwjXVaoiyH:rk:4f:0

There are many vendors of this on ebay.

Sound card impedance bridge -

http://www.marucchi.it/ZRLC_web/ZRLC/Steber_An_LMS_Impedance_Bridge.pdf

http://www.sillanumsoft.org/ZRLC.htm

Regards, Dana.

Of course you risk frying your sound card so bear that in mind before taking this advice.

The better advice is to buy a cheap USB scope. There are many on eBay and other places.

#### Arjune

Joined Jan 6, 2018
131
I designed digital circuits for many years with a voltmeter and a logic probe. For clocks, you just need a frequency divider to make it slow enough to see with a visual indicator.

Why are you using a BJT and a MOSFET? One or the other should be sufficient.

Is there a current limiter in CM1?

EDIT: To answer your question, it can drive TTL, but you should decrease the voltage to 5V.
I don't know of a current limiter in CM1, the clock is powered with a 1.5v cell. I am using the 2n7000 because a BJT output was 4.3v only (I need 5v) as an emitter follower. My logic probe indicates that hi and lo levels are fine with the schematic circuit I provided.

#### spinnaker

Joined Oct 29, 2009
7,835
I am afraid to use the sound card, I don't want to lose my HP laptop. The USB scope on ebay for $27 sounds promising. Is there an installation disk for software? If so, what kind? I think that$27 is a stand alone. But I would consider spending a bit more and getting the Hantek. It would make it a lot easier for you to share wave forms on the forum.

#### dl324

Joined Mar 30, 2015
11,563
I don't know of a current limiter in CM1, the clock is powered with a 1.5v cell. I am using the 2n7000 because a BJT output was 4.3v only (I need 5v) as an emitter follower.
When the transistor is off, the output should be supply voltage. It's the load that's causing the voltage to drop.

Replace D3 and D4 with 1k resistors, change R4 to 1k. and take the output from the collector of the BJT. High level output voltage should be 5.25V.

Joined Mar 10, 2018
4,057
There are many decision to make buying a scope. Some points -

1) Battery operated scope intrinsically isolated. See following for why this
is important in some situations.

https://www.newark.com/pdfs/techarticles/tektronix/FFM.pdf

https://www.tek.com/document/application-note/three-facets-floating-measurement-solutions

https://www.picotech.com/library/oscilloscopes/differential-and-floating-voltage-measurements

2) Triggering capabilities go from basic to extensive. On you tube you can see videos
on advanced scopes, look at one just to give you an idea of what triggering does for
you.

3) Infinite persistence on a scope very useful. Look at noise, like on supply rails.

4) Anything that plugs into a PC or Laptop can take it down. Its a fact of life. A scope
plugged into USB and trying to do line measurements tricky, read the ap notes above.

5) Some basic math capability, like subtract Chan B from Chan A.

6) Two channels and ability to do basic differential measurement quite useful.
And this is a way of making safe measurements over single ended measurements.

7) 10X probes are your friend.

8) If you can get it FFT on scope very useful. 6022BE seems to have it.

Just a few, there are threads on this forum discussing low end and other scopes. Take
time to investigate. You are in no hurray to buy the wrong solution.

Here some reviews of 6022BE - https://www.eevblog.com/forum/testgear/hantek-6022be-will-it-work-for-me/

Most scopes vendors allow you to download software to look at it, try before you
buy (to some extent). Manuals of course rich in info.

Regards,. Dana.

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#### Arjune

Joined Jan 6, 2018
131
When the transistor is off, the output should be supply voltage. It's the load that's causing the voltage to drop.

Replace D3 and D4 with 1k resistors, change R4 to 1k. and take the output from the collector of the BJT. High level output voltage should be 5.25V.
I'd try aliexpress.com. Here's a 200mmX120mmX75mm box for $8 (on sale). Thread Starter #### Arjune Joined Jan 6, 2018 131 I'd try aliexpress.com. Here's a 200mmX120mmX75mm box for$8 (on sale).
Looks good and free shipping. It looks like it's not transparent but it says it's clear and wiring would show through. We need to hide wires so people wouldn't think it's dangerous.

#### dl324

Joined Mar 30, 2015
11,563
Looks good and free shipping. It looks like it's not transparent but it says it's clear and wiring would show through. We need to hide wires so people wouldn't think it's dangerous.
Free shipping may not last because the current Administration is in a trade war with China.

Lead times are listed as 30 days or more. I've found that they're conservative in their ETA's. That particular box is only on sale for a few more hours. After that, it's closer to the $10 you paid on eBay. Chinese sellers also list on eBay. Thread Starter #### Arjune Joined Jan 6, 2018 131 Free shipping may not last because the current Administration is in a trade war with China. Lead times are listed as 30 days or more. I've found that they're conservative in their ETA's. That particular box is only on sale for a few more hours. After that, it's closer to the$10 you paid on eBay. Chinese sellers also list on eBay.
I don't think the Hantek 6022BE is for windows 8 operating system. I am running Windows 8.1 on my HP laptop. Am I wrong?

#### DickCappels

Joined Aug 21, 2008
6,593
To the question in the OP, yes the output should get very close to ground. I should able to clock TTL but the 1k + LED load may give you trouble getting an output voltage that is a reliable high state for CMOS or TTL. I suggest buffering the LED.