Digital volume control circuit schematic
Controls & Timers
This is digital volume control circuit that Can be applied to the normal volume of a power amplifier. When press switch S1 adds up the volume and press switch S2 to reduce the volume down. How it works IC1 is a 555 CMOS Timer Single IC will be connected in astable flip-flop model as pulse frequency generator up / down to input pin of the counter IC2-74LS193, through push-bottom switch S1 (Up) and S2(Down). Changing wide of pulse signal from IC1 may replace R1 with potentiometer. To begin with, when we press the switch S1 (increase sound) binary output will …
High Temperature fire Alarm Circuit using transistors
Alarm systems
This is high temperature fire alarm circuit, when the temperature rise exceeds the limit, it will sound the siren rang out. It is easy to use with transistor circuit to detects heat. Then, a loud noise of the sirens with IC packages. How it works We uses the combination between Q1 (BC109), which is silicon NPN transistor and Q2 (AC188) which is PNP germanium transistor To detect heat in case of fire. Then, the siren will sound warning beeps. The collector lead of Q1 is connected with Base lead of Q2, while the collector lead of Q2 is connected with …
FM transmitter circuit without coil
Basic Circuits
This is FM transmitter circuit without Coil,using inverter digital IC as main and controlled frequency is precise by crystal. Figure 1 the circuit diagram In Figure 1 is RF oscillator circuit which use a inverter IC1/2 and ceramic crystal filter 10.7 MHz to use drive IC1/4 – IC1/6 by through IC1/3. When inverter in parallel form this impedance output is low thus they can drive directly an antenna. When output of IC1/4 – IC1/6 are square wave which have much more internal harmonic. The harmonic number 9 of frequency 10.7 MHz (96.3 MHz) will take place at the center of …
Modem wireless router overheating troubleshooting
Basic - Tools & Tips
This is Modem wireless router overheating troubleshooting by my son. If your Internet is very slow in the daytime is The modem wireless router is overheat. My son measure its temperature was about 55 degrees Celsius. As Figure 1 So we figured out a way to reduce the heat to it. The right way is to install a fan to air absorbs heat quickly. Blowing into it Not what should be avoided due to the dusty lot. There may be problems later. Then He used a screwdriver to open the box as Figure 2. To drill holes in the bottom …