Monday, July 28, 2014

Guitar Fuzz Effect

Welcome back! Anyone who plays guitar for a long time knows this fuzz effect. It's kind of a vintage effect but it still is cool. This fuzz effect module can be bought but why don't you try making one for yourself? In this post I'm not going to go into the in depth mechanism, I will post more about op-amps and will explain in there.

Diagram and a few lines


IC 741 is a very basic op-amp, it can be swapped with any low noise op-amp for better performance.

The input and output 0.47uF capacitors can be replaced with lowered valued capacitors for more trebley response. For more bass response a small valued capacitor can be added in parallel with the 1Mohm resistor.

1Mohm resistor can be replaced with a variable resistor, which will give you the option for controlling fuzz amount.

If the output volume level is too low, you can use a small amplifier to boost it up!
See how.

This circuit takes up a very small amount of current so a single 9V Alkaline battery or six AA sized battery can be enough for this.

It is a very small circuit so it can be built directly into the guitar.

You can experiment a lot with it!

Good luck!

Read my other posts here

AC Live Line Detector

Good Morning everyone! Hope everyone is doing great! Now I'm going to post a very small diagram that can be used as an AC main line detector even if it is buried under plaster. 

So what do we need?

1. CD 4017  Decade Counter with 10 decoded outputs.
2. 0.1uF non-polar polyester type capacitor. (can be replaced with a 47uF electrolytic)
3. Red LED.
4. Single Pole Single Throw(SPST) Press Button.
5. Probe made of 5-20cm long, stiff insulated piece of wire. Can be used 15Amp cables for this.

Now the diagram!

Live Wire detector
 
How it works?

To understand how this circuit is going to work we have understand the purpose and action of the IC CD 4017. In simple word #14 pin is the input clock pin for this IC, when it gets a clock it starts counting which means it will give output to its 10 decoded output pins one by one. So a 100Hz clock will result in each output pins giving a 10Hz output. 

#3 is one of its output pins, you can use any other output pin.

#16 Pin is for supplying positive voltage and #8 is for negative or ground reference.

#15 pin is the RESET pin, we are keeping it low so that the counter keeps on counting.

#13 is for clock inhibit, we want to advance the count one step at the positive clock signal transition. For that we have to keep this pin at low. So we hook it up to the ground reference point.

If the probe is brought closer to a live wire, capacitive coupling between the live wire and the probe clocks the counter. and causes the LED to flash, and as I said earlier the any of the output pins will get only 1/10th portion of it(as it has 10 output pins so yes that's logical) so the LED will flash 5 times in the 50Hz 220V line and 6 times in the 60Hz 110V line.

Keeping it away from the Live wire will eventually lower or breaks the capacitive coupling and thus the counter will stop and the LED will turn off.

Making The Probe!

5-20cm long and stiff insulated piece of wire can be used. Usually those used in high current applications such as powering up an air-conditioner. Sensitivity of this circuit can be varied with the length of this probe.

Powering up the circuit

This circuit can run from 3V only, two AA sized battery can do this. And because of using 3V supply no need to use current limiting resistor with the LED.

It can work with up to 18V supply but going over 3.5/4V will require a current limiting resistor with the LED.

Hope it will help! Happy Experimenting.

CD 4017 Datasheet for more information.

Read my other posts here!

Wednesday, July 2, 2014

Auto Power Off Circuit To Protect Home Appliance

Ramadan Mubarak to everyone. In this post I will be showing you guys a very simple circuit to protect your home appliance from sudden power failure for short time. What often times happen is when the power returns the voltage level can be a bit too high. So to protect the appliance we need to make a circuit that will cut off the conducting path to the appliance even after the return of AC power. You have to manually turn it on to restart the appliance. You can also use different modifications so that the circuit can be triggered at different AC main line voltage levels and essentially make a low and high voltage cut off circuit too.






What we will need?

1. Transformer to step down AC main line to something usable on relay like 15V.
2. Relay, should be chosen in a way that can handle the appliance.
3. Diodes for rectifying, protecting and Capacitors for smoothing and filtering.
4. Voltage Regulator to drive the relay without any unwanted noise or
5. Press button to activate the circuit.
6. Neon lamp and resistor as indicator.

Circuit Diagram


Auto Power Off Circuit

Component Description:
 
220V(110V) AC is provided via two wires, one of which is directly connected to the load(preferably the Neutral one) and the other(the Live one) is connected via a Relay and a press button.

Transformer that will drive the relay is also connected to the load in a parallel manner.

100Kohm resistor and the neon lamp will work as an indicator.

The 0.1uF capacitors are used for suppressing high frequency. The 470uF and 220uF capacitors are used as smoothing capacitor.

First four IN4007 diodes is connected as bridge rectifier, thus it will convert AC into DC. Another IN4007 diode will protect everything from the relay.

The 7812 is used for regulating purpose. Relays tend to generate noise or hum on unregulated power supply. Moreover it is better to feed a constant voltage to the relay to ensure it's proper working.


Mechanism:

Mechanism of this circuit is pretty simple and straightforward.

When the 220V AC IN is hooked up to power source, the load won't turn on because one of the wires is connected to the Normally open terminal of the relay. If we hit the "press button" once what it will do is provide power to the load and high side of the transformer momentarily. But in the mean time the relay will turn on as the power was available for the transformer. If the press button is released afterwards the load will continue to run.

But if the main 220V AC IN is lost the relay will automatically go to normally closed and thus if the power is back again the load won't run unless the press button is pressed again.

Warning: 

1. As this circuit has 220VAC connection with it, be sure to know what you are doing.
2. Before changing anything remove AC main power. 
3. Before connecting this circuit to AC main power check the circuit thoroughly for shorted connection or wrong connection.
4. Make sure to use components that will be enough for the load.
5. Double check relay's rating before connecting a load. Don't give higher than rated voltage on its electromagnet neither hook up more than rated load.
6. All capacitors should be rated higher than source voltage. 35V would be fine.
7. 7812 shouldn't be that hot. In case if its hot, attach a heat-sink to the regulator with some thermal paste.

That's all for now! Happy experimenting! Read my other entries here!