I am using a 555 IC to produce a sound in a small 8 ohm speaker. It works just fine, but the square wave sounds rather harsh. I am wondering if there is a simple way to round out the corners to make it sound better. All the circuits I have found online are rather complex. It seems to me that a simple RC circuit should do the trick, but I have not been able to figure out how to position it.  Any help would be greatly appreciated.
122291
I have square waves of different frequencies (1KHz to 20KHz), and I need to convert them to a sine wave of the corresponding fundamental frequency.  A RC ladder Low-pass filter was the first thing which I tried, It gave good results but the output peak-to-peak voltage (Vpp) varied a lot with the frequency. The square wave has a Vpp of 3.6V. But after filtering, the output Vpp of the sine wave varies from 3V to 2V as the frequency increases.  Is there any other better way to get a pure sine wave from square wave of same frequency without this voltage drop?  Thank you
15791
I have an analog signal which ranges between 0V and 10V.  I want to linearly scale it down to 0 to 2.5V for my ADC.     I'm concerned that using a resistive voltage divider will affect signal quality.  Is this true?  If it's not true, what value resistor should I use for voltage divider?
1040
I have a front end module that generates an (ECG) signal that varies from +/-2.5 V. I want to shift this signal to 0 - 5V. What is the best way to do this? Would a summing amplifier like the below circuit good enough? With R1 = R2 and V1 = 2.5V, V2 = my signal, V3 = V4 = GND
50238
I have built numerous 555 circuits over the years. I recently had to built a Monostable 555 cct. as per this site :    The cct. is used in a motor vehicle. When the remote control is pushed to open the doors, it sends positive 12V to this Monostable cct. to initiate it and a 3 Amp Power Transistor pulses the siren momentarily to indicatse "unlocking" by audible means.   The issue I have is that Rt and Ct used to time the output pulse is not short enough. I replaced these components to the smallest values I could get, but the output is still "too long". Teh siren makes a "chooow" sound instead of "chow". Sounmds too unprofessional or after-market.  Any ideas to get a short pulse (nearly a few micro seconds) out of this old 555 cct. ?
38601
My PCB design software comes with some libraries that include some common components, like chip resistors and capacitors.  I have noticed, however, that the footprint land pattern for the 0805 resistor is not identical to the 0805 capacitor.  I then did some googling, and discovered multiple IPC standards that don't seem to quite agree with each other.  Is there a reason an 0805 resistor would have a different land pattern than an 0805 capacitor?  Is there a "best standard"?  IPC-7351, IPC-SM-782, or what?
104185
EDIT:  Please read the whole post before automatically down voting. I KNOW the diagram is crap.  That is what I am asking about.  It isn't my diagram.  Original post:  I Web searched a bit and searched this site, but I didn't really see a good answer.  I thought line level voltage was insufficient to switch a transistor and I thought an audio signal coming out of an amp or preamp was a sine wave anyway.  I thought those things made the seemingly simple idea of driving LEDs to pulse with sound or music a little more difficult.  Microphone input -> preamp -> rectify it to make a nice fat on/off dc signal -> drive something.  But I see this:    with a circuit that looks like:   I see other circuits (one at Instructables I think) that essentially do the same thing- connect the line level voltage directly to some transistors.  My question: I haven't a clue what is going on here.  Why does this work- or does it really?  What is happening?  Is it that the "audio source" is really headphone/speaker level and not the line level it may be billed at and thus enough to saturate the transistor?  Does this look like a recipe for disaster?    EDIT:  Trying to focus things per Red Gritty Brick.  I know the diagram is crap.  How would you do it right?
53454
Under normal circumstances, the Dell E2310Hc LCD Monitor seems to work fine.  However, when I display an large array of hash characters ("#") a faint buzz can be heard from the monitor.  It appears to be correlated to the periodic pattern somehow:   Increasing the size of the pattern (i.e. changing the font size) changes the frequency of the noise. Adding more pattern enhances the sound. Increasing the contrast increases the intensity of the sound. Color does not seem to affect the sound. Increasing the contrast of the pattern w.r.t. the background increases the sound. Edit: Horizontally tiled patterns make little contribution, but vertically tiled patterns cause the majority of the noise.   What could be causing this?  I also noticed the same issue with another LCD monitor but it's a lot less perceptible.
81311
I am trying to find a 1k linear digital pot which has a very low (preferably 0) wiper resistance. Any interface would be ok (apart from just up/down).   I found this article:  resistance  which could be a way around the issue.   What I am trying to do, is substitute the 1k pot in the classic fuzz circuit     with a digitally controlled one, and it needs to pretty much go down to 0 Ohm to get the full fuzz effect. I am not sure if the above 'trick' may interfere the fuzz's simple circuit which is extremely sensitive.  Does anyone have any suggestions, feedback or alternative idea?   Thanks!
70509
this is my first question and I am very much a beginner in electronics so I apologize if this is a too stupid question.  I have Atari punk console and another small homemade audiomaking circuit. These two have mono audio signals as outputs and I would like to combine these as one in the simplest possible way. I know next to nothing about audio processing but I believe that the strength of the two signals is roughly the same.  What would a neat solution be? It would be really nice if I could extend the solution later on to more than just two signals but thats not really important.  Any hints, references, guides, links or ideas would be highly appreciated.
64484
What is Offset null in 1st and 5th pin in IC 741 (Op-Amp)? Why it is used, though it is not used in many circuits? Give me explanation regarding the offset null! Why offset voltage was formed in IC 741?
4985
I've noticed that whilst I have a well-known solution using an NE555, that IC doesn't fulfill my needs perfectly. Others have told me that the NE555 is very rarely an appropriate solution to one of the problems it's being used for.  What are the systematic problems with the NE555?  More specifically, I'd like to have a better (lower part count / complexity, better stability, lower power consumption) solution for the following typical applications:   One-off timer (Monostable Multivibrator) Ramp generator Dear versed reader: please extend this list with typical applications!
100057
Wondering why you would choose to use smaller capacitors in parallel vs one bigger one.  Here's an example:      Is this a component size and track width choice?  Thanks!
113747
Here is the figure:   All tutorials have an inductor in smsp-buck. But when I simulate without an inductor I see a similar plot. Why not use only a capacitor?
95420
I am trying to model a violin belly and I am intrigued, how is it possible to make faces with soft / rounded edges?    The edges I do are totally straight (see the blue amoeba).  Also, do you have some idea on how to avoid the edge loops getting too "compressed" in the middle of the model (see the red amoeba) ?    I know the Subdivision surface modifier, but I want curved edges after applying the modifier... like in this picture :  Any help will be very appreciated. Thank you in advance!  Marcos  2nd part  In fact, I've tryied to model using nurbs and bezier curves, but I wasn't able to find any tool similar to loft that works with curves, then I was forced to convert it in meshes, the results were not terrific and I've started to move the vertices manually, a real pain... Unlike a guitar, each edge loop is on a diferente elevation on z axis and I have to keep the original dimensions, So I have to be extremely careful when using the subdivision suface modifier. I've already modeled this think on three different CAD softwares, but the meshes are far from good... I want to improve the edge loops, but it will be a long path... Thank you again.
54154
First, let me say that I'm no electrical engineer, I'm just a curious student.   Here's a photo of a Raspberry Pi A+.    I (as one completely ignorant of PCB design) would expect the electrical paths to be as simple as possible, which normally implies using the shortest path from the source to destination. Here, the printer can clearly print straight diagonal paths, but some other nearby paths are stair-stepped, or even take bizarre roundabout paths to their destinations.  I've seen this on a variety of PCBs, including other models of the Raspberry Pi, some Arduinos, computer motherboards...  Can you explain, in layman's terms, why these more complex paths are chosen?
57423
Lots of chips nowadays require smoothing capacitors between VCC and GND for proper function. Given that my projects run at all sorts of different voltage and current levels, I was wondering if anyone had any rules of thumb for a) how many and b) what size capacitors should be used to ensure that power supply ripple doesn't affect my circuits?
104598
Whenever I'm making a cheap, 2-sided PCB, I run into this problem:    Where I have signal lines (on the top layer here) running over top of a big fat power trace (on the bottom layer).  Now, this is obviously terrible because there is no good return path on the bottom side.  For issues like this, Hott consultants has a good recommendation:    However, I wonder if a solution like the one below is also acceptable.    My intuition tells me yes, this solution is ok.  Over the break in the ground plane, the current will hop over the vias and then back down to the lower plane.  Some back of the envelope math tells me that this adds a trivial amount to the loop area, and therefore a trivial amount to the return impedance.  Can someone tell me...   How right / wrong my intuition is here about using vias? If my intuition is wrong, why? Also, if my intuition is wrong, what is the correct solution in this sort of situation (2 layer, with power traces under signal)?   For the record, these particular signal lines aren't terribly fast (500 kHz), but I would like to know how to deal with this situation when I have signals in the 5 - 10 MHz range.  Edit  Below is a screenshot of about 60% of the board.  Maybe it will help with the critique