MP

uh....yeah.... I am sure they are just doing that to fool the noobies.... ::) MP

Claudio, I have much more trouble with Portugese when I am in Brazil than what you seem to be having with English on this forum. Welcome to the forum! MP

yeah....whatever.... ::) ...guess it was just luck that got me my Engineering degree.... you technicians could teach us a lot. MP

Well, I just got back from a business trip and found your post. No. I am not wrong. Some of the guitar effects which use a 1K input resistor to the op-amp are: Ibanez Graphic EQ MXR Flanger Ross Stereo Delay Ibanez TS9 Tube Screamer Ibanez TS-808 Tube Screamer MXR Hot Tubes Distortion MANY MANY more........ Also, note that you are mis-quoting the "experts" regarding the guitar pick up. All guitar pick ups have loading provided on the guitar circuitry under the plate. You do not need to add it. Guitar pickups do not connect directly to the jack. I have actually been one of these guitar effects "experts" since the mid 70's. Also note that the C1 and R1 combination makes for a low cut frequency calculated as C=1/ (6.28)*(Low Cut off freq in HZ)*(R1). MP

Not always. They are used both ways...which is another example of situations that do not require this resistor. MP

Don't use an LM386 as a pre-amp. It will be too much for your guitar amp. MP

R3 has no direct effect on the impedance of the guitar pickup. The value of R3 is selected to provide two things: 1. amplification with respect to the feedback resistor and 2. Filtering as per calculation with C1. You guys missed the input cap. Jesus and Aaron win the prize with the effect that will not load down the guitar pickup as the volume is changed. MP

Jesus, There is nothing wrong with the design of your fuzz circuit. In fact, it is an older classic fuzz circuit from the 60s or 70s as I recall. I recommend that you check for mis-connection. Also, I would recommend that you replace the 1N4001 diodes with 1N914. You could even replace these with LEDs and the circuit would work. Also, I suggest that where you have a 1Meg ohm resistor, make this a 1K ohm resistor with a 1M pot in series. This will give you a level of fuzz adjustment. Note that it will also act as a volume control. MP

You just need to make sure your negative lead on the power supply output is 1.2 volts lower than the common connection of the LM317. The output of the power supply does not have to have it's zero potential connected to the "ground" pin of the LM317. Does that help? There are a number of ways to do this. You can purchase a -1.2V precision reference IC, use voltage dividers, op-amps, additional regulators, transistors, etc. BTW....LM317 is a positive voltage regulator. If you are going to use another regulator for a negative voltage reference, you would want to use the LM337 for this. It is a negative adj. voltage regulator. MP

There are many applications where a resistor between base and emitter is not needed on a transistor. "Always" is certainly an exaggeration. Also note, protection from radio waves requires filtering. A resistor does not protect against radio interference. MP

Perhaps this drawing makes it more clear? MP

Mohammadamirbazr, Please ignore those who want to argue about religion. Have you looked at Atmel AT43USB353M? It might be what you are looking for. MP

These are all good tips no matter what project you are working on. Thanks for sharing with everyone. MP

It is my understanding that allowio is part of porttalk. Just download porttalk. You can find several links through google. MP

This topic has been moved to Circuit/General Requests. [iurl]http://www.electronics-lab.com/forum/index.php?topic=6263.0[/iurl]

There will be no voltage between the third prong (Uninsulated or Green wire) and the return (White Wire). Also, you should have full potential between the Hot (Black Wire) to Return (White Wire) and also see full potential between the Hot (Black Wire) and the Ground (Green or uninsulated Wire). This should be the same potential. You should also see no potential difference between the wall plate screw and Return or Ground. This tells you that the receptacle box is also grounded. The Return and Ground follow separate paths in the wiring, but are connected at the power box where the ground will save you if you have an open in the Return. (Provided that the appliance is setup for this protection). Hope that helps. To insure the ground is always working, you can install a GFCI type receptacle, which will open up the circuit in the event that the ground is not good. MP

I agree. Have you asked Mike about this? I will notify him of this topic. MP

You should post a location since International shipping would not be worth while. MP

I assume you are trying to use as little board space as possible? I design with "surface mount" tantalums instead of "through hole" Electrolytics in such a case. Solves many other problems as well. I would not recommend metallic or ceramic caps for power supply bypass. Hope that is helpful. MP

Hey gogo, Sorry for the late reply. I was on a business trip in Asia for the week and just got back this morning. Here are the eagle files for both schematic and board. Feel free to make any changes you need. This zip has a parts list for the LEDs used in the design if you would like to use them. Otherwise, you might have to make changes to the schematic for the one you want to use. Also, you might be able to use one of the edit commands to just use a different package in the board layout. MP icl7107-7106.zip

Not really a good idea, but if you do this, you will need to clean the board with alcohol, flux all parts that you will heat, then clean all the flux off the board when finished and apply a conformal coating to the board to re-seal all of the solder connections so they do not corrode. MP

How much charge did it provide? Full battery for a reasonable lifespan? Sometimes AC pulses will give you what looks like a revived charge circuit. You can sometimes bring a dead battery back to life by pulsing the charge voltage to it. If the battery only took a little more charge, it is possible that this is what you saw. If the battery now boasts a full charge and the charging system is no longer failing, then I would agree with the comments above about a cold joint or cracked solder pad. In this case, you should get out the magnifier and see what needs reflow. MP

Don't stare at it too long.... ;D As I understand it, the dots will start to connect. MP

just curious why you chose transistors for a car alarm instead of digital gates, like OR gates and AND gates to make some logical choices of when and why an alarm is set. MP

It's a double sided board. I think you are trying to mount them on the wrong side. MP