KVL and output from arbitrary waveform generator (AWG) - Page 1
Forum section: electronics / beginners

author: 2d72
author_rank: Newbie
timestamp: March 19, 2021, 06:50:44 pm
content: Hi,I'm a newbie that just started with practical electronics after 2 years of theory.I'm using an AWG (hantek 2d72) just in series with 2 1k resistors and when I measure, with the scope, on either of them I don't see any voltage drop in them.I'm really intrigued as I think there would have to be a proportional voltage drop in each resistor, for example:5v square wave = 2.5v (first resistor) + 2.5v (second resistor) , like in the link below:http://www.falstad.com/circuit/circuitjs.html?ctz=CQAgjCAMB0l3BWcMBMcUHYMGZIA4UA2ATmIxAUgoqoQFMBaMMAKADdwU9wAWHz7igSEo4ED1qiqMBCwBOA3v1z8wfUWHgsA7iGwIUIFClVcjwqPL2RV6-YeP8qmuCwD2Ywk-GRS1GHCEQqKGENgsQAWhat am I missing?PS: I was trying to make a really basic diode clamping circuit but I had to forget about it and try to review my understanding of the AWG ...Many thanks in advance

author: rstofer
author_rank: Super Contributor
timestamp: March 19, 2021, 10:23:02 pm
content: I don't know anything about the 2D72...From page 24 of the User Manual, I get the idea that you can use the device for an AWG or a Scope but not both concurrently. Note that they display the sine wave on 'an' oscilloscope, not the tool itself. That idea seems consistent with the 'Scope', 'DMM', 'AWG' menu keys. It's pretty clear that you can't use the display for the 'DMM' function and the 'Scope' function at the same time.But, what do I know?Take the signal generator output and loop it directly to a scope channel and see what happens. Trust me, Kirchhoff's Laws hold.You also need to settle on 'ground'. The shield of the generator is ground as are the shields of the scope probes (or at least they should be). So, all of them need to go to the same point, the bottom rail of the schematic. This means it is easy to measure the voltage on the lower resistor but it is not possible to measure the voltage drop across the top resistor because you can't put the probe ground at the intersection of the two resistors.https://www.circuitspecialists.com/content/476383/HANTEK2D72_Manual.pdf

author: gf
author_rank: Super Contributor
timestamp: March 20, 2021, 09:38:37 am
content: AWG and scope can be used concurrently (only the display can't show both simultaneously), but yes, ground is shared between AWG, scope and USB connector. The DMM is isolated, though.

author: 2d72
author_rank: Newbie
timestamp: March 20, 2021, 09:55:05 am
content: Hi,This week I bought a new breadboard that seems to have slightly difference rails.When I was taking a photo for you guys I decided to move the bottom rail "bridge" closer to the components and everything started to work ...New components, new traps for noobs.Many thanks guys!!

author: tggzzz
author_rank: Super Contributor
timestamp: March 20, 2021, 11:20:46 am
content: Have fun debugging the solderless breadboard, then move onto debugging your circuit.https://entertaininghacks.wordpress.com/2020/07/22/prototyping-circuits-easy-cheap-fast-reliable-techniques/

author: Ian.M
author_rank: Super Contributor
timestamp: March 20, 2021, 11:35:14 am
content: AAhhhh....Breadboard Traps For Young PlayersSee that gap in the red and blue lines along the bus bars? That indicates the bus bars are in two sections, not electrically connected. To use them as a single bus bar you need to add a jumper to join each at the gap. This gives you more flexibility when working with multiple voltage rails.