Table Lamp with auxiliary 12v Automotive Style LED Light

This circuit provides about one watt of non-isolated DC power for an automotive type 12v LED array lamp in addition to a standard incandescent table lamp.

Ac-to-DC converter

This circuit includes a PMOS enhancement-mode FET input buffer amplifier, coupled to a classical absolute value circuit which essentially eliminates the effect

This circuit includes a PMOS enhancement-mode FET input buffer amplifier, coupled to a classical absolute value circuit which essentially eliminates the effect

60 watt audio amplifier project using STK4038

Using the STK4038X audio amplifier IC, can be designed a very simple high power and efficiency audio power amplifier . This circuit is manufactured by Sanyo Corporation and will provide a output power of 60 watts on a 8 ohms load or 4 ohms load with 0.008% distortion .
The output power that is provided by this audio IC , can be more higher , but with more distortion.
If you will use a 8 ohms load you must power this audio amplifier project from a dual +/- 40 volts DC power supply and if you’ll use a 4 ohms load you must power this audio project form a dual +/- 33.5 volts DC power source.
To prevent over heating the STK4038X audio power IC must be heatsinked on a good heatsink .
Also you must use a very well filtered power supply ( a 10000uF capacitor will be fine for this audio project) .

Remote on-off switch

This circuit provides power control without running line-voltage switch leads. The primary of a 6-volt filament transformer is connected between the gate and one of the main terminals of a triac. The secondary is connected to the remote switch through ordinary low-voltage line. With switch open, transformer blocks gate current, prevents the triac from firing and applying power to the equipment

Caller-ID-Display-Service

If you got a multimeter and a phone you can start testing. Check the voltage across the pair, should be 48VDC in US, 60VDC in Europe.
Place a 600 ohm resistor, 5W across the pair and measure the current should be 20 to 40mA (holding current)

While on-hook the Ring will have a negative voltage and the Tip will be grounded through equipment at the Central Office UNLESS the office is a "Floating Battery" type office. In the latter case the Ring will have a negative voltage and the Tip will have a positive voltage. The sum of the two voltages (which are in series) will be about 48 to 52 Volts.
The usual way of doing this is to use a bicolor LED that glows read with one polarity and green when the polarity is reversed. You just put a resistor in series to limit the current. I think the ones I have usre 3.3k, maybe more if the voltage is high. the max current for a phone line is 60 mA, so it would be wiuse to put 3 or 4 diodes in series in each direction to absorb any excwess current above 20 mA or so. But the dissipation of the resistor may be more than a half watt. So use a couple in series or a 1 watter.
BTW, if you plug one of these into a wall jack, the polarity will be correct, but the modular line cord flips the polarity so that it's
reversed at the phone jack. So you have to know where you're testing.

2 Watts FM transmitter

This is a nice 2 Watts FM transmitter. It has a Super-Sensitive pre-amplification with BC109 and BC177 with more than 100% signal modulation. The job finish the 2N2219 by Motorola. For the Coils you should use 1mm wire(enameled), L1= 3 turns - 10mm diameter, L2= 1 turn - 10mm diameter. R9 trimmer controls the modulation gain. The tunning is easy by controlling C9 trimmer (88-108 MHz). The RFC J should be the VK220J with ferrite (VK200 is not suitable).

Robot-Eyes

An infrared LED and a phototransistor are used for each eye. Half of a 556 timer IC (ICl-a) functions as an as table multivibrator oscillating at a frequency of about 1 kHz. That IC drives transistor Ql which in turn drives the two infrared LED's, LED1 and LED2. The right eye is composed of LED1 and Q2. If an obstacle appears in front of the right eye, pulses from LED1 are reflected by the obstacle and detected by Q2. The signal from Q2 is amplified by Q3, which triggers IC2, a 555.

Light-Controlled-Lamp-Switch

A school drama needed lamps that automatically turned on and off when spot lights did the same. Lamp switching had to be wireless, durable, dependable, simple and inexpensive. With stage and spot lights off, very little light falls on the CdS photocell, so its internal resistance is several megohms and Rl keeps the gate of Ql at nearly zero volts, which keeps it off.

Flame-Monitor

Monitoring a flame and directly switching a 120-V load is easily accomplished using the Ll4G1 for point sources of light. For light sources which subtend over 10° of arc, the L14C1 should be used and the illumination levels raised by a factor of 5.

Sun-tracker

In solar cell array applications and solar instrumentation, it is desirable to monitor the approximate position of the sun to allow efficient automatic alignment. The Ll4Gllens can provide about 15° of accuracy in a simple level sensing circuit, and a full hemisphere can be monitored with about 150 phototransistors. The sun provides `` 80 mW/cm2 to the L14Gl when on the centerline. This will keep the output down to,; 0.5 V for f),; 7.5°. The sky provides `` 0.5 mW/cm2 to the Ll4G1 and will keep the output greater than 10 V when viewed.