Automated Crib Lights

Device purpose:

This circuit is intended to drive the various lights decorating the crib prepared during Christmas season at many homes in Latin Countries, especially for children delight, in order to obtain realistic light-effects.


Features:

• Alternating day and night with lights gradually dimming from full-on to full-off and the opposite.
• Slow turn on of model-houses interior as night approaches, and slow turn off as sun rises, with presettable intensity, thus imitating candles' light for a more realistic effect.
• Flickering ever-running circuit driving bulbs for fires, firesides, lanterns effects etc.
• Total cycle duration: 2 minutes. Day duration: 1 minute, 15 seconds. Night duration: 45 seconds. (All values are approximate).

Parts:

• R1___________150K 1/4W Resistor
• R2,R9,R14_____22K 1/4W Resistors
• R3,R11_______220K 1/4W Resistors
• R4,R12________10K 1/4W Resistors
• R5___________100K 1/2W Trimmer Cermet
• R6,R7,R13,R15__1R 1/4W Resistors
• R8____________33K 1/4W Resistor
• R10__________270K 1/4W Resistor
• R16___________47R 1/4W Resistor
• C1,C4________100nF 63V Polyester Capacitors
• C2,C6_________10µF 25V Electrolytic Capacitors
• C3,C5________100µF 25V Electrolytic Capacitors
• D1-D3_______1N4148 75V 150mA Diodes
• IC1___________4060 14 stage ripple counter and oscillator IC
• IC2__________LM324 Low power Quad Op-Amp IC
• IC3__________78L12 12V 100mA Voltage regulator IC
• Q1,Q3,Q5_____BC238 25V 100mA NPN Transistors
• Q2,Q4,Q6_____BD681 100V 4A NPN Darlington Transistors
• J1___________Miniature input socket,
• suited for commercial plug-in variable voltage power supplies
• J2-J5________Two ways output sockets

Load requirements:

• Input J1 is connected to a commercial wall plug-in power supply transformer adapter with variable output settled to 12-15Vdc, and a required minimum output capability of 600mA @ 12V. Using a good number of bulbs the output capability must reach about 1.5A.
• Output J2 is connected to a permanently-on 12V 1W blue bulb(s) for night effect.
• Output J3 is connected to several 12V 2.2W bulbs in parallel for sunlight effect. Max. output current: 1.2A (i.e. 6-7 bulbs).
• Output J4 is connected to several 12V 1W or 1/2W micro-bulbs in parallel for house-interiors lights. Max. output current: 600mA (i.e. 7-8 1W bulbs, doubling in number if 1/2W).
• Output J5 is connected to one or several 12V 1W or 1/2W micro-bulbs in parallel for fires, firesides, lanterns effects etc. Max. output current: 600mA (bulbs total number same as above).
• All outputs are current limited, and short-proof for a reasonable lapse of time.

Circuit operation:

IC1 oscillates at a frequency calculated to obtain a pin 2 level change around every minute. IC2A is then enabled to slowly charge and discharge C5 through R10 during a 2 minutes period. IC1 pin 9 drives D2, R3 & C4, generating a sawtooth for IC2C & IC2D comparators. IC2D comparing the voltage at pin 13 with the sawtooth, generates a squarewave with variable mark-space ratio driving the output darlington Q2 for daylight bulbs. IC2B changes its output at a threshold voltage settled by R8 & R9, activating IC2C & Q4 that act like IC2D & Q2 driving model-houses bulbs as evening approaches and turning them off at dawn. R11 & C6 provide slow turn on and off and R5 sets the basic brightness of these bulbs. IC1 pin 7 drives the output darlington Q6 for flickering fires bulbs and R16 prevents them to turn off completely for a more realistic effect. Q1, Q3, Q5 and associated Base resistors provide current limiting.

Notes:

• Total period length can be varied changing C1 and/or R1 values.
• Day-night ratio can be varied changing R10 value slightly.
• Threshold voltage of turn on and off of model-houses lights can be varied changing slightly R8 and/or R9 values.
• Turn on and off speed of model-houses lights can be varied changing R11 value.
• Current limiting can be varied changing Q2, Q4 & Q6 Emitter resistors.
• Heatsinks for Q2, Q4 & Q6 are needed if current limits are increased.

Cranial Electrotherapy Stimulator

Current generated flows through clips placed on the earlobes Output current adjustable from 80 to 600 microAmperes

Device purpose:

Owing to the recent launching in Europe of Cranial Electrotherapy Stimulation (CES) portable sets, we have been "Electronically Stimulated" in designing a similar circuit for the sake of Hobbyists. CES is the most popular technique for electrically boosting brain power, and has long been prescribed by doctors, mainly in the USA, for therapeutic reasons, including the treatment of anxiety, depression, insomnia, and chemical dependency. CES units generate an adjustable current (80 to 600 microAmperes) that flows through clips placed on the earlobes. The waveform of this device is a 400 milliseconds positive pulse followed by a negative one of the same duration, then a pause of 1.2 seconds. The main frequency is 0.5 Hz, i.e. a double pulse every 2 seconds. Some people report that this kind of minute specialized electrical impulses contributes to achieve a relaxed state that leaves the mind alert.


Obviously we can't claim or prove any therapeutic effectiveness for this device, but if you are interested in trying it, the circuit is so cheap and so simple to build that an attempt can be made with quite no harm.

Parts:

• R1_____________1M5 1/4W Resistor
• R2____________15K 1/4W Resistor
• R3___________100K Linear Potentiometer
• R4_____________2K2 1/4W Resistor
• C1___________330nF 63V Polyester Capacitor
• C2___________100µF 25V Electrolytic Capacitor
• D1_____________3mm. Red LED
• IC1___________7555 or TS555CN CMos Timer IC
• IC2___________4017 Decade counter with 10 decoded outputs IC
• SW1___________SPST Slider Switch
• B1______________9V PP3 Battery
• Clip for PP3 Battery
• Two Earclips with wires (see notes)

Circuit operation:

IC1 forms a narrow pulse, 2.5Hz oscillator feeding IC2. This chip generates the various timings for the output pulses. Output is taken at pins 2 & 3 to easily obtain negative going pulses also. Current output is limited to 600µA by R2 and can be regulated from 80 to 600µA by means of R3. The LED flashes every 2 seconds signaling proper operation and can also be used for setting purposes. It can be omitted together with R4, greatly increasing battery life.

Notes:

• In order to obtain a more precise frequency setting take R1=1M2 and add a 500K trimmer in series with it.
• In this case use a frequency meter to read 2.5Hz at pin 3 of IC1, or an oscilloscope to read 400msec pulses at pins 2, 3 or 10, adjusting the added trimmer.
• A simpler setting can be made adjusting the trimmer to count exactly a LED flash every 2 seconds.
• Earclips can be made with little plastic clips and cementing the end of the wire in a position suited to make good contact with earlobes.
• Ultra-simple earclips can be made using a thin copper foil with rounded corners 4 cm. long and 1.5 cm. wide, soldering the wire end in the center, and then folding the foil in two parts holding the earlobes.
• To ensure a better current transfer, this kind of devices usually has felt pads moistened with a conducting solution interposed between clips and skin.
• Commercial sets have frequently a built-in timer. Timing sessions last usually 20 minutes to 1 hour. For this purpose you can use the Timed Beeper the Bedside Lamp Timer or the Jogging Timer circuits available on this website, adjusting the timing components in order to suit your needs.

Digital Capacitance Meter

This is a simple capacitance meter which can measure capacitance value easy. There are some measurement methods for capacitance, at one time the capacitance was measured with a impedance bridge or a dip meter. Recently typical capacitance meters can measure capacitance and some additional characteristics from current vector by applying AC voltage to the Cx. Some simple capacitance meter use integration method that measureing transient response of the R-C network. There are some construction kits based on this method.


This project uses the integration method. There is an advantage that the resulut can be got as a digital data directly because it bases measurement of time, accurate analog circuit is not required and its calibration can be done easy by using a micro controller. Therefor the integration method is suitable for hand built capacitance meter with high realizability.

Hardware

To measure a charge time, only a voltage comparator, a counter and some glue logics are needed. However, a microcntroller (AT90S2313) is used for this project to realize the system easy. In point of fact, I had thought that analog comparator in the AVR is not useful. But I found that the compare output can also be used as a captureing trigger of TC1. This is a nice feature for that use :-)
The integration circuit can be simplified like shown in the circuit diagram. The threshold voltage is generated by divider registers. It seems not stable to valiation of supply voltage however the charge time is not affected by the supply voltage. You will able to find that voltage terms can be erased when apply formure 2, VC1/E term is dtermined by only divide ratio. This advantage is the essence found in the NE555 timer IC. Ofcourse the supply voltage must be steady during integration.

According to the foundation, measure integration time with only one threshold voltage will do. However input voltage of near ground level is little difficult to use due to following reasons.

• Voltage not drop to 0 volt. Capacitor voltage will not be discharged to zero volt. It require a time to discharge capacitor to sufficientaly low voltage for measuring operation. It will expand measureing interval. Saturation voltage at discharge switch is also increase this effect.
• There is a time beween start to charge and then start timer. It will cause a measurement error. This can be ignored on the AVR because it requires only one clock cycle for that sequence. Any other microcontroller may rquire to consider this problem.
• Leakage current on analog input. Accrding to AVR data sheet, the leakage current on analog input is increased near zero volt. This will cause a measurement error.

To avoid to use near zero volt, two threshold voltages VC1(0.17 Vcc) and VC2(0.5 Vcc) are used and measure t2-t1(0.5RC). This can avoid avobe problems and comparator delay/offset will also be canceled. As for the leakage currnet, circuit board should be kept clean to minimize surface leak.

The supply voltage is generated with a DC-DC converter powered from a 1.5V AA cell. The swiching power supply is not suitable for measurement circuit but it seems not affected by ripple voltage because two ripple filters are applied. I recommend to use a 9V 6LR61 battery and a 78L05 instead, and do not omit BOD or you will be afflicted with EEPROM data collaption.
Calibration

When power is on first time, full segment, "E4" and ten several pF will be displayed. This value means stray capacitance on the circuit. The stray capacitance can be canceled by SW1. Two reference capacitors of 1nF and 100nF are needed to calibrate the capacitance meter. If you could not obtain the reference capacitors, accurate capacitors within ±1% can be used insted. This capacitance meter does not have any trimmer pot, it performs the calibration by reading the reference capacitor and saving gain adjustment value in full automatic operation.

To calibrate low range: First, adjust zero with SW1. Next, tie pin #1 and #3 of connector P1, set a 1nF reference capacitor and push SW1.

To calibrate high range: Tie pin #4 and #6 of connector P1, set a 100nF reference capacitor and push SW1.

"E4" at power on means calibration value in the EEPROM has been broken. It will never be displayed if once calibration is performed. As for zero adjustment, it is not saved into the EEPROM, it will require each time power-on or any jig is attached.

Free Firmware

Computer Controlled Frequency Counter/Logic Probe

This circuit is a stable frequency counter accurate to 5 significant digits. The range is 0 - 30MHz with an input sensitivity of greater then 100mV. The probe connects to the PC serial port. So by using the crystal oscillator already present on your PC serial card and software calibration, the Probes' external circuitry is kept to a minimum. Probe 9 can also be used as a logic probe/analyzer using included software (LPROBE92.EXE).


Parts

• R1,R2,R3,R4---- 4 100K 1/4W Resistor
• R5 ------------ 1 10M 1/4W Resistor
• R6, R7 ------- 2 3.3K 1/4W Resistor
• R8 ----------- 1 390 Ohm 1/4W Resistor
• R9 ----------- 1 1M 1/4W Resistor
• C1, C4 ------- 2 0.1uF Ceramic Disc Capacitor
• C2, C3 ------- 2 100uF 16V Electrolytic Capacitor
• D1 ----------- 1 1N4148 Signal Diode Any 200mA silicon signal diode
• D2, D3 ------- 2 3.3V Zener Diode
• D4 ----------- 1 6.2V Zener Diode
• U1 ----------- 1 74HC00 Quad Highspeed NAND Gate
• U2, U3, U4 ---- 3 4021 8 Stage Shift Register
• U5 ----------- 1 74HC393 Dual Highspeed 4 Bit Counter
• U6 ----------- 1 4040 12 Stage Binary Counter
• MISC --------- 1 PC Board, Wire, Suitable Probe, DB9/DB25 Connector

• The software to use this probe can be downloaded using the following link. Note that this software is compiled for Intel x86 platforms and runs under DOS, Win95, Win98 and WinMe. It does not run under any Windows version based on NT including Windows NT 3.51, WinNT4, Win2K, Win2K3, WinXP and Windows Vista. This is because NT based operating systems do not allow direct hardware access.

Probe Software, Zipped, 19K

• SETPROBE.EXE is the frequency counter calibration program. To give accurate readings the Probe must be calibrated to your PC. SETPROBE.EXE calculates the constant error correction factor for the particular PC serial card the probe is to be used on. The frequency counter corrects for this slight constant error in crystal frequency by using the correction factor contained in PROBE.DAT. To calculate this correction factor, a reliable oscillator of known frequency (eg 2MHz Crystal Oscillator) is required. When CALIBRAT.EXE is run, the Probe will sample the frequency and then ask for the true frequency value in HZ. The frequency entered must be to 1 Hz accuracy (no decimal points) or an error will occur (for example "200123" not "200123.34" or "2003.421 kHz"). The program then calculates constant error correction factor and stores it to PROBE.DAT. Calibration is only necessary once.
• LPROBE92.EXE is the logic analysis program . Logic states are displayed in real time. This program runs best under DOS (not a DOS window). The sampling speed is adjusted by using the left and right arrow keys.

The three triggering modes are:

• TRIG: Starts each scan (left-right of screen) on a negative going edge of logic signal.
• KEY TRIG: Waits for a key to be pressed before beginning each scan.
• FREE RUNNING: Not triggered.

• To Toggle between these use the UP / DOWN arrow keys. To quit from LPROBE press escape.
• FPROBE92.EXE is the frequency counter program. The measured frequency is displayed in Hz with commas indicating KHz and MHz. To quit from FPROBE press any key.
• Serial port pinouts are as follows.