# Tag Info

16

Instead of just poking at random values and asking what difference they make, stop and actually think about the circuit. Once you understand what each part does, you'll be able to find acceptable values for them yourself. Q1 and Q2 are arranged with positive feedback so that they have two stable operating points. When Q1 is off, Q2 is off, which then does ...

13

Although an edge is a well-defined moment in time, it is not true to say that level-triggering also does not have a well-defined moment in time. It does. There is a well-defined moment in time when the level of the clock falls, the inputs to the clocked circuit are sampled, and further changes in inputs are no longer admitted. The issue with level ...

10

Generally trigger on sharper edges when possible. That will result in less time uncertainty and therefore jitter. It also minimizes the time the digital input is held in the in-between region. Some digital inputs don't react well to being held there. They can oscillate and/or draw higher current. When you have unavoidably slow edges, you need to use a ...

9

I would like to suggest that the comparator circuit shown by @hwengmgr could use some small improvements over what was posted. Improvements include: Bigger capacitor value to reduce filter effect of the capacitor at frequency. Larger value resistors in dividers to reduce current load on source supply. Added hysteresis at the comparator to make the circuit ...

7

Think what would happen if the scope didn't trigger at all - it would display several cycles of a sinewave (e.g.) across the screen and then continue to display a 2nd series of sinewaves but they would not be superimposed on top of the first set of sinewaves because the chances of the sinewave frequency exactly matching the timebase scan time is very, very ...

7

I've done exactly what you're trying, back in the day. It's possible. First, learn to use the single sweep function. Let's say your setup looks like simulate this circuit – Schematic created using CircuitLab Set your scope to trigger at 2 - 3 volts, negative edge. Set the time base for about 2 - 5 msec/div. Set the brightness fairly high. Now turn ...

6

I think you could get enough energy from the sound card to trigger a fet and this could turn on a relay. Any sound card should be able to produce a frequency of 10kHz and a few schottky diodes and a couple of capacitors will generate enough voltage for a fet to turn on and activate a relay. The relay could have to latch (using a spare contact to bypass the ...

5

Here is a simple circuit that will cause a relay to be closed when a sufficiently strong audio signal is fed in. A small 12 V relay should only need 10-15 mA to turn on, and then be able to switch a few amps of current. You probably need to turn up the volume on the computer output as high as it goes. Added: Here is a circuit that is slightly more ...

5

I too was wanting to know what trigger sensitivity was, and how it related to the trigger level. I found this article which explains it. http://www.rohde-schwarz-scopes.com/_pdf/Benefits_of_RTO_digital_trigger_system-White%20Paper.pdf Basically the trigger sensitivity sets the hysteresis level. In a complex waveform a trigger level may be crossed several ...

5

You probably have some sort of trigger filtering or delay turned on. Otherwise, a regular rising edge trigger should have caught the first pulse, not waited until the second. Look carefully thru the trigger menu and turn off anything called a "filter", "delay", "holdoff", and the like.

5

If its a continuous waveform, you can use a DC blocking capacitor and then use some resistors to set the DC common mode point and scale it as well. Then feed it into an LM339 comparator to get your digital output. Something like this. I have NOT calculated the resistor ratio's! But setting R3 will let you attenuate the incoming waveform. R4/R5 sets the ...

5

Take this schematic : simulate this circuit – Schematic created using CircuitLab Playing with Ohm's law, you get : $R_{3} \times R_{1}\times V_{R}+R_{3} \times R_{2} \times V_{P} = (R_{1} \times R_{2}+R_{1} \times R_{3}+R_{2} \times R_{3}) \times V_{A}$ If you set VR=0, VA shall be equal to VP/2=1.65V. You get : \\$R_{1} = \dfrac{R_{2} \times R_{...

5

There are a few different ways of doing triggering on a scope and they all have various tradeoffs. For low end scopes that sample slow enough to use an MCU of some sort, this can be done in software. But this sort of scope isn't really something I would consider a true scope, either a low end 'toy' or a low bandwidth data acquisition unit of some sort. ...

5

The circuit basically consists of 3 sections: Q1 + Q2 + R2 - R5 forming the latch Q3 + SW1 + SW2 to set the latch in a certain state Q4 to drive the load Changing R2, R3 will make the latch work or not. I think that for both sets of resistor values the latch will work. I prefer the R2 = 5.1 kohm, R3 = 1 kohm situation because when R2 = 300 ohms a lot of ...

5

This will provide sharp trigger pulse with hysteresis; you can finetune the time by Rp: At time zero the supply turns ON and provides a 5V two seconds single trigger pulse output.

5

Figure 1. Trace breaks at 0.2 divisions and restarts at almost 4.5 divisions. Figure 2. Trace breaks at 0.2 divisions and restarts at almost 4.25 divisions. The problem isn't your 'scope - it's the signal. You have jitter of at least 0.2 / 4 = 5%. You can usually confirm that the 'scope is stable using the 1 kHz test signal present on the front panel of ...

4

This same signal triggers just fine using a Tektronix TDS3014, with trigger hold off values ranging from 350μs to 1.5ms or more. I think the answer, therefore, is to cross-check signals with more than one scope when something doesn't look right. I was never able to get the BK 2542B to properly show the clock without either missing the first pulse, or ...

4

To understand why edge triggering is preferred, imagine an 8-bit adder hooked up to a register, constantly adding 1 to the value of the register, with a push-button wired to the enable pin of the register. If the enable pin of the register is level-sensitive, then the contents of the register will constantly increment for the duration of the button press. ...

4

The 465B has two time base, A and B. The B time base is called delayed time base and can be used to zoom on a portion of a signal to see it in greater details. You can also trigger on this zoomed signal by using the trigger B (and the "DLY" is for "delayed" or "delay"). You can watch some videos from w2aew on youtube here. He has differents tutorials on ...

4

In the trigger menu (right side below the trigger level knob: "menu") you can, if you have it (I think Timeout might be in the upgrades? You could hack it if you don't have it anyway) you can select Timeout. You then set slope up and down and a timeout of 75% of the sine period, in the case of 50Hz AC that would be 15ms. It will then trigger when no slope ...

4

No they can't. The power supply, in this case the generator, must be able to supply enough power for it to work. The transformer is not able to magically increase the power output of the original power source. Instead it will waste some in the process of transforming the voltage, so you get even less power out of it. You need a bigger generator for this ...

4

Your question is very short on detail, and you should think about WhatRoughBeat's questions in comments, and come up with some specifications. However, when you are starting, it's difficult to do that in the abstract, so here's an example circuit, a straw man, to get you thinking about why specifications are needed. There are many ways to implement your ...

4

1) There are several waves plotted on top of each other. If you want that: it is normal. If you don't want that: try adjusting the scope settings such that you get only one trace. For example use "single shot" mode. 2) It might be normal, depending on how you set the triggering to work the scope might not trigger reliably making it wait in between. If you ...

3

If I had to guess, I would bet that T6 and T9 are probably testpoints on the PCB for use by the engineer or technicians at the factory. And I'd double-down on my guess that those testpoints are connected to digital outputs from a microcontroller. That's just a guess. But if I'm correct, then attempting to source any significant current out of a MCU's ...

3

Volume, or in this case, audio amplitude or sound pressure, is a dynamic/variable thing. In other words, it will vary based on location and position of microphone, frequency and duration of the source audio, etc. A little something to think about: When you watch a documentary video with a narrator and background music, there is often an audio effect called ...

3

ETA - Regretfully, I have to declare what follows (pertaining to option 1) to be mistaken. Upon further thought, I have concluded that the basic approach does not meet the requirement for driving a 1 Mohm load, and cannot be made to do so. Those kind souls who upvoted me should probably reconsider. With your requirements, this should be pretty ...

3

On a digital scope, once the waveform is in the digital realm, bit resolution is quite important. As the bit resolution needs to be no greater than the screen resolution it is convenient to express trigger sensitivities as a fraction of the signal as displayed on the screen. For example on my Tektronix digital scope, if the waveform displayed is much below ...

3

Edge-triggering is good for clocks, because it allows the value output by a latch in response to one (e.g. rising) clock edge to be used in the computation of what it should do on the next rising clock edge. If one is constructing a sequential circuit such as a counter using a number of edge-triggered latches, one may arbitrarily mix fast and slow logic ...

3

You can't use the main timing resistor and capacitor to generate your trigger signal. As you discovered, this is exactly equivalent to the astable configuration. Instead, you need to provide a separate resistor (to Vcc) and capacitor (to ground) for the Trigger pin. The time constant for this pair should be short relative to the main timing period, but long ...

3

Sounds like a job for a 555 timer configured as a monostable, see for example - http://www.doctronics.co.uk/555.htm#monostable

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