It is called analog dial timer as it has no digital display, but the chip is digital it is CD4541. It is Mains operated, you could make on-delay or off-delay. By changing the caps and resistors or with even dip-switches you could get timing of few seconds to many hours. Circuit is Analog Timer 4541 .
Some timers energize the relay after a set delay on power start. Some start with relay energized and turn off after set time. Motors and big systems cannot take fast turn-on and turn-off, Some systems will require sections or modules to start one after another as they are interdependent. So Timers in automation were made to effect such delays, the early ones were mechanical clockwork.
The CD4541BC Programmable Timer is designed with a 16-stage binary counter, an integrated oscillator for use with an external capacitor and two resistors, output control logic, and a special power-on reset circuit. The special features of the power-on reset circuit are first, no additional static power consumption and second, the part functions across the full voltage range (3V¨C15V) whether power-on reset is enabled or disabled.
- Available division ratios 28, 210, 213, or 216.
- Increments on positive edge clock transitions.
- Built-in low power RC oscillator.
- Oscillator frequency range . DC to 100 kHz.
- Power on Auto reset initializes all counters.
Volume control circuit for speaker 4 ohm or 8 ohm located in the another room far away. by using only passive components. This gives limited control and helps reduce volume when a conversation starts. The resistors are very low value.
Passive volume control
A simple circuit you can build at home at low cost it uses just a rotary switch and wire wound resistors. Add more resistors and a rotary switch with more contacts for finer control.
More Hobby Ideas and Projects at Hobby DIY Garage
An easy project to start DIY electronics is the Guitar Speaker. Make a good Acoustically friendly Wooden Box. Add a 20 Watt Audio Amplifier and a Large Speaker, There is a Power Supply too in this box. If you hear a Large Hum over the Strumming of the Guitar. You are in Business.
You should know that this is a limited design, it is used when the speaker is far away from audio amplifier. In the early days audio amps were made of power transistors and signal transistors. (they came after valves), No remote controls, Radio tuners, Spool Players and Turntables would be connected to these via a Preamplifier and Rotary Switches.
The Speakers in large wooden boxes would be kept at the far corners of the Hall, you could have a passive volume control in this with a Neon flickering indication of audio. That circuit is here Music Sound to light converter.
The basic digital circuits are Flip Flop and Counter, both are here. This circuit can be cascaded to make even a 6 digit event counter, even a simple frequency counter can be made.
These are best done with microcontrollers today. Then what if you have to design your own microcontroller on a FPGA, so the basics have to be sound, hence you have to know what gates, flip flops and counters are.
see the seven segment display. Inc, Dec, and Set buttons are momentary acting and Clk Button is latching type. The Dip Switch in the also can be set.
a. – Set the DIP Switch as you like and then Press the Set button. The BCD value will be at the 4029 output, The Decimal value will be seen in the seven segment Display. Now try for different dip switch settings and see the BCD and Decimal output.
b. – Now Press The Inc and Dec pushbuttons. Set it to Increment up-count or Decrement which is down-count. This is a simple flip flop control.
c. – Now Click the Clk – clock or count button, the switch will latch, press it again to release. If you toggle it once the counter will get a single pulse and it will count it, see the BCD and decimal displays. Now you turn it on and leave it, the counter will keep counting one per second till you turn it off, the clock nand gate is wired to be an oscillator.
The decimal point LED of display is given to Carry Out pin of 4029 so observe this at 9 and 0 or transitions.
Add 104 CD, 0.1uF ceramic disc cap to all the ICs across the supply pins. Also add a 104 CD cap across Inc switch and one across the Set switch for power on default settings.
See a Tutor Digital up down BCD counter that will help you take the first step in digital electronics.
This circuit is built around LM3647 an Universal Battery Charger, This Circuit is an untested design. It is based on application hints and was provided as an example to the user. This circuit gives a 12V DC from mains or battery and the battery is also charged when power resumes.
U1D monitors charge current and U1B monitors battery voltage these values are the feedback to charge controller U3. U1C drives Q2 to Control the charging process by switching in PWM. The LM7812 with a 2N6107 Current Booster Regulate the battery and mains DC to a 12V for powering the Product Circuits.
Li-Ion Battery Charger – del90005
Portable electronics have got a big boost due to batteries like Li-Ion. Here is a decade old circuit to charge a large battery. It can be scaled up or down in power. It has current and voltage limit protections.