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brmarcum

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29Instructables762,517Views225CommentsWashington State, USA
I've always loved to figure out how things work, so hacking and making just fits for me. I'm a husband, a father, an EOD technician, an automation engineer at Schweitzer Engineering Laboratories, and a proud graduate of Washington State University. Go COUGS!!

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  • brmarcum commented on brmarcum's instructable AC to DC Conversion
    AC to DC Conversion

    Thanks! I appreciate the feedback.Regarding the first question - yes. DC/DC converters have a VDC input range where they will work properly and output the regulated voltage. I use a 24VDC buck-boost converter at work quite frequently and it has a 9-36VDC input range. So as long as the input stays in that range, it should output nominal.For the second question, I'm a bit confused. I've used the same DC/DC converter I mentioned above on a rectified AC/DC circuit to produce clean VDC, but I use it far more often on DC voltage from batteries. Most often it's for boosting 12VDC on an engine battery to 24VDC for the engine control electronics. My confusion is your reference to the V_reg. Are you wanting to stage several converters in line, like 12VDC battery through a buck converter to 9VDC the…

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    Thanks! I appreciate the feedback.Regarding the first question - yes. DC/DC converters have a VDC input range where they will work properly and output the regulated voltage. I use a 24VDC buck-boost converter at work quite frequently and it has a 9-36VDC input range. So as long as the input stays in that range, it should output nominal.For the second question, I'm a bit confused. I've used the same DC/DC converter I mentioned above on a rectified AC/DC circuit to produce clean VDC, but I use it far more often on DC voltage from batteries. Most often it's for boosting 12VDC on an engine battery to 24VDC for the engine control electronics. My confusion is your reference to the V_reg. Are you wanting to stage several converters in line, like 12VDC battery through a buck converter to 9VDC then through a V_reg down to 5VDC? In theory, yes that will work, but I wouldn't do it. More devices introduces more losses along the way, and there are already devices that can handle significant swings between input and output. For the 7805 listed above, the max input voltage is 35VDC, so you wouldn't need anything else between your initial DC source and the V_reg input pin.Hope that helps.

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  • Semiconductor Curve Tracer With the Analog Discovery 2

    Thank you so much. The entire purpose was to make it approachable and easy to follow using portable and low cost hardware.Your version looks great as well. A quick review of your achievements and credentials makes your comment that much more valuable and appreciated. Cheers!

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  • Easy Under-Cabinet Lighting

    The transformer steps down the AC mains voltage (120VAC or 240VAC) to a level that the LEDs can handle. The LEDs I used are 12VDC, but since they are diodes, they can handle 12VAC, just not 120/240VAC. There are LEDs that exist that can handle 120VAC, but none that I've seen in strips like this. They're used in electrical substations for single indicator lights.So yes, you need the transformer.

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  • Semiconductor Curve Tracer With the Analog Discovery 2

    Correct. The data acquired from the analog discovery can appear different than the data acquired from the electronics explorer if you don't take the differential inputs into account. The negative side of all scope channels on the EE board are tied together to a common ground, while a good curve tracer needs fully differential inputs to plot the data in real time. However, if you take two sets of data separately with the EE board, one with channel one and then another with channel two, you can export each set of data as a CSV file and then use a spreadsheet program like Excel to combine and plot the data to build the curve that way. It takes extra steps but the results should be the same, and is essentially what you are doing in Waveforms by adding the math channel and the XY plot. Also re…

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    Correct. The data acquired from the analog discovery can appear different than the data acquired from the electronics explorer if you don't take the differential inputs into account. The negative side of all scope channels on the EE board are tied together to a common ground, while a good curve tracer needs fully differential inputs to plot the data in real time. However, if you take two sets of data separately with the EE board, one with channel one and then another with channel two, you can export each set of data as a CSV file and then use a spreadsheet program like Excel to combine and plot the data to build the curve that way. It takes extra steps but the results should be the same, and is essentially what you are doing in Waveforms by adding the math channel and the XY plot. Also remember that different devices will show different results. You may need to "tune" your viewing window and plots to see all of the data based on the actual device used and not just assume the same nominal behavior for all devices.MOSFETs are voltage controlled devices, and a curve tracer is most useful for current controlled devices. The "controllable," or operating, region of most voltage controlled devices tends to be much steeper and narrower than for current controlled devices as well, so the ability to adjust the input in a way that you could get a meaningful plot of V_in vs I_out or V_out would be very challenging. It requires very fine adjustment on the input, and in theory this circuit should work with a MOSFET with the correct modifications. It's likely that the voltage steps as described are too large for a MOSFET and you're skipping right over the operating region and it goes from off to on with no ramp or curve in between. Keeping R1 in the circuit could also prevent the MOSFET from even turning on in the first place. I would start somewhere in the range of 1k for R1 and then go lower from there. You may find, and I suspect, that removing R1 completely works fine.

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  • Using the Spectrum Analyzer With the Analog Discovery 2

    I don't believe that the tool has that function built in. You can however use the SDK for the Waveforms application to build your own tools using Javascript.

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  • Monitoring Digital Circuits With the Digital Discovery

    Your question is very open ended and undefined. I can't determine what you need help with.

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  • No, this circuit will not turn off when you wave your hand in front of it. This circuit will turn on with motion and then stay on for a set amount of time. All motion will be ignored once it has turned on, but once it turns off you can move in front of it to turn it on again.

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  • The AD654 voltage controlled oscillator is what generates the carrier frequency based on the values of the timing capacitor and timing resistor. The equation can be found in the datasheet.

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  • Changing the inductance of the coil will affect the circuit's resonance frequency, which for this circuit becomes its transmission frequency. The same is true for changing the capacitance on the trimmer cap. Since adjustable caps are easier to make than adjustable inductors, you hard set the coils of your inductor and then use a trimmer cap.To change the range you need to use a larger power supply and make sure your components can handle the power running through them.

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  • brmarcum commented on brmarcum's instructable AC to DC Conversion

    You're stepping down your AC too far.You need to supply voltage regulators with at least 2 volts more input than you expect on the output. So with the 7812, if you want 12V out, you have to supply it with at least 14V bare minimum, preferably over 15V. That 15V is the output from the diode bridge, which will also drop the voltage about 0.7V per diode. The current travels through two of the four diodes at any point in time (all four are still used though) so the input to the diode bridge needs to be at least 17VAC.The datasheet four the 7812 will list the max input V at around 30V (double check that), so if you use a 10X step down transformer that outputs ~22VAC you should have no problems, though you may need a heat sink on the 7812.Your setup as is will only provide enough voltage to dri…

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    You're stepping down your AC too far.You need to supply voltage regulators with at least 2 volts more input than you expect on the output. So with the 7812, if you want 12V out, you have to supply it with at least 14V bare minimum, preferably over 15V. That 15V is the output from the diode bridge, which will also drop the voltage about 0.7V per diode. The current travels through two of the four diodes at any point in time (all four are still used though) so the input to the diode bridge needs to be at least 17VAC.The datasheet four the 7812 will list the max input V at around 30V (double check that), so if you use a 10X step down transformer that outputs ~22VAC you should have no problems, though you may need a heat sink on the 7812.Your setup as is will only provide enough voltage to drive a 7805 5VDC voltage regulator or lower.

    Good question. Thank you for providing sample data. It makes it easier to pinpoint the solution.Cheers

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  • brmarcum commented on bekathwia's instructable Bullet Journalling

    I really like this idea. And your art is beautiful.I would recommend people follow the link you provided to the Bullet Journalling website. It gives a fantastic overview of the core principles but without the artsy embellishment.Your I'ble is also well done. Clear and concise with tons of illustrative (and did I mention beautiful?) photos. Nice job.

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  • This is really cool. Nice design and build. Good I'ble as well. Clear and concise.I even have a spare 5-ton bottle jack laying around...

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  • brmarcum commented on brmarcum's instructable 555 Timer Basics

    C1 is a filtering cap on the power supply. It's a universal component in most electronic circuits to filter out small but rapid fluctuations in the voltage source. Depending on the stability of your source, you can remove it, but it's good practice to always use one. The value is dependent on the power requirement of your circuit.The idea is that if the input voltage from the source drops, the capacitor acts like a short term backup battery and tries to maintain the input voltage until either the source recovers or the cap runs out. Larger caps will take longer to drain, but also take longer to fill. If your circuit requires a fair bit of power, a small cap may not be able to supply enough electrons to properly filter the source fluctuations since it would drain too quickly.

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  • brmarcum commented on androkavo's instructable Wooden Digital Clock

    Bro.What the...I can't...How did you...Could this be any cooler!?

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  • That's really cool. Nice design.

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    • Programming Digilent FPGAs Using NI Multisim
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  • That Gerber tho!! HAHAHAI've always heard powder coating was simple and easy. Nice work.

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  • Thanks gzumwalt! As is usually the case the solution here was both simple and elegant. Nice work.

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  • brmarcum commented on brmarcum's instructable 555 Timer Basics

    I apologize for the confusion. The text should have referred to C2 and not C3. I have now fixed that. The values for C1, C3, and C4 as shown in the schematic are default values that I almost always use when I connect a 555, but none of them have any effect on the 555's performance as an oscillator.C2, R1, and R2 are the components that directly effect the oscillation frequency and duty cycle. Those values are chosen based on your requirements for your circuit. The nominal values as shown were chosen at random for this particular project, but will produce a 3.1 kHz signal at 66.67% duty cycle. You can do the math the long way or use a calculator like this one.I hope that explains it better.

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  • I'm completely blown away by this project. Especially since it was for your school. This looks like a professionally manufactured unit. Very well done.Your I'ble is well done as well. Good flow, tons of clear pictures, and everything clearly explained.Nice job.

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  • Impressive. Nice work.

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  • brmarcum commented on gzumwalt's instructable Four Whistles Version 2

    I am so thoroughly impressed by your designs. Simple and plain, yet at the same time elegant and well designed.If at all possible, I would love to see a separate Instructable on how you designed the cylinder. How did you determine the size, shape, length of the note, etc. in order to accurately play the song? How many cylinders ended up in the bin before this one was the one that worked?

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  • This is cool, but where's your I'ble on video editing?

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    • Monitoring Digital Circuits With the Digital Discovery
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  • brmarcum commented on makjosher's instructable A Simpler Tripod

    Impressive. Nice work.

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  • That's really pretty. Nice project.Well planned Instructable as well. Clear and concise with the right pictures showing the right concept at the right time. Nice work.Except for one thing. The YouTube video showing basic quilling shapes is blocked by Sony Music Entertainment (SME). I assume they didn't like the music you used and since they own the copyright they are flexing their giant iron fist. Overlay some different music and load it again, you should be good. I'd like to see it.

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    • Using the Voltmeter With the Analog Discovery 2
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  • I think metal might work better as it is less prone to wear compared to wood.Maybe some kind of a cam style clip that has a small indentation on the saw side of the clip that would catch on the lip of the saw's base plate. There would be a noticable 'click' feel as the indentation fell into place over the base plate. This would make it harder for the vibration to overcome the tension holding the saw up.

    I'm thoroughly impressed. Well done. I wouldn't use it for fine furniture, but you make the point that it's not for that use anyway.Two thoughts I had. The first is how well do the clips hold the saw to the underside of the table? Does the vibration of the motor loosen them over time? The last thing you need is for a clip to give out in the middle of use. So many bad days.The second is how to maintain the 'squareness' of the rip fence. In the video you can see the end of the fence opposite the user (nearest to the camera) flex as you push material through. Any thoughts on how to secure both ends so the cut stays square?

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  • This is really cool. Simple yet functional, like every tool should be.

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