Mains-Power (Page 2)

This is a mains 230V AC load current indicator and is a LIVE CIRCUIT, so take care. The Resistors have to be a fusible ceramic wire wound.

More at Mains Voltage and Power Circuits

Mains Current LED Indicator

This circuit has been drawn from my memory and i have not tried it out again, just see if it is ok and then try. You should use the fuse of 1A a slow blow if you want but it is very important. You can design the shunt R3 and Fuse rating as required by your load.

Note that this circuit is to be put in series with the load like an ammeter. If you put it across the supply like a voltmeter it will fuse out or burn out. This circuit has to be enclosed in a plastic sealed enclosure to avoid contact.

The circuit uses opto-coupler MOC3041 of Motorola and the Triac BTA16-600 of STMicro as a solid state switch or relay. Four Switches boost or buck the mains voltage, keeping output within limits.

Power Electronics Design Methods

It also uses the LM324 quad opamp from National Semiconductor which is low power and single supply. As the MOC3041 switches the Triac at zero crossover there is no inter-winding short of transformer on crossover hopefully, the control circuit is designed in such a way that more than one triac will not be turned on at a time, i would like you to give feedback.

555 multivibrator like power oscillator

This circuit is a design concept, not tested by me and i did it just to explain some ideas.

Solid-State Stabilizer Step up 110V AC

The triac will switch at zero cross over because of MOC3041, hence no problem of an interwinding short, but then control circuit may fail or malfunction, so use fuse as shown . Also a snubber made of a 47E resistor and 0.02uF 630V pl cap in series must be placed across each triac.

Battery and Energy Management

Use heatsinks for all parts that heat, air circulation. Use Presets with series resistor as required so that you can test or calibrate. This Stabilizer should not be used with Inductive loads like motors or solenoids it may be ok for lighting and small electronics. If input voltage is 230V put the two 110V windings in series in proper polarity. BTA16600 is a ST part, metal tab is electrically insulated, 16A and 600V.

All mains wiring and connections should be designed for high voltage and current, They should be isolated visually from control circuits by 10 mm or more.

It can Stabilize Mains voltage to around +/- 10% . It can be used for both 110V AC or 220V AC inputs with modifications. The Output is 220V AC. There is an overload, under voltage and over voltage trip circuit.

Mains Stabilty and Supply Regulation

U2A and U2B are two comparators which controls relays K2 and K3 Respectively. One Boosts the voltage (Step-up) when mains supply is low. The other Bucks the voltage (Step-down) when mains voltage goes beyond a limit.

UPS Power Inverter and DC to AC

U2C and U2D work like a window comparator to trip the unit above and below certain preset limits. This circuit is clubbed with a Mains control relay K1 which can be Turned ON-OFF with two pushbuttons.

Stabilizer Step up 110V AC to 230V AC 500VAThis circuit is a design i did, not tested by me as yet.With some tweaks and modifications it might work.

Put a 0.1uF 1KV pl cap across all relay contacts to avoid sparking. Relay current paths should be large and direct to supply, or when relay operates ground will lift and cause malfunction.All mains wiring and connections should be designed for high voltage and current, They should be isolated visually from control circuits by 10 mm or more. If input voltage is 230V put the two 110V windings in series in proper polarity.

Electric double layer capacitor an eFlywheel

Put one LED with resistor for boost and buck indication if required. Use Presets with series resistor as required so that you can test or calibrate. The 1M dead band or hysteresis resistor can be varied from 330K to 10M as performance demands, this resistor stops oscillation or chattering of relays.

A Center tap 50Hz Step Down Transformer with two diodes is used to get a train of Positive Sine Pulses at 100Hz which is applied to Q6 base via R51. 2N2646 is a unijunction transistor(UJT) in a TO-18 metal package. The control voltage or voltage proportional to error is fed to R56-Q3, The UJT drives a pulse transformer which provides isolation from the Load which the SCR bridge is controlling. This phase angle control gives a near Linear closed loop control for a SCR bridge which may be used in Electroplating or a Preregulator of a big power supply.

2N2646 based Voltage controlled SCR Pulser

This is a Normally Closed PCB Mount SSR. That means when DC Control input is low, the triac is ON, the output passes the load current to turn on small heater-motor-lamp or a bigger contacter-drive etc.

NC Solid State Relay or SSR

When input DC is high the output is OFF. This is also Optically Isolated from Mains. A Microcontroller output which is buffered by some driver can drive this relay. It is better that in big systems these SSR Modules can be on another PCB, to avoid mains wiring near Logic circuits. But this cannot be used for medical electronics, or critical applications. More reliability and visual isolation of voltages may be required for such equipment.

NC AC Load SSR DC control

EMI RFI Filters are required in two situations, to prevent EMI from an Electronic Equipment Like A Dimmer, Thyristor Drive, SMPS or Switcher affecting other Modules in a System or Neighboring Equipment. The Second Situation is when a Sensitive Equipment Like a Medical Apparatus or Precision Measuring Instrument has to be Immune to any Noise from outside, as it can affect performance. EMI RFI Filter

Sometimes it is Accuracy that can get affected, but some electrical jolts can damage or desensitize fine sensors or positioning systems.

On the right you can see a Filter that i used to make long ago, This is connected in series with an Existing Mains Chord. It can also be Fixed in a Control Panel with a Clamp. One Y cap is Missing in this Piece. The Big one must be the X cap a higher Capacitance Value. The Y cap is Lower Value and withstands around 1kV, It is better if X cap is AC 440V.

Related Resources

Here is a Neon Flasher circuit (untested) for a user request at Circuits FAQ. This can be built into a switchboard or a gadget for indicating Live Power.

D1-C1 form a simple half-wave rectifier, The Cap charges to peak voltage and can store charge for a long time if there is no bleeder. So while building it take extra care. This forms a DC supply across C1. C1 is a Plastic High-voltage cap, IN4007 has a 1KV rating, so it is ok for 230V rectifier.

R1 Charges C2 and when C2 reaches 60-80V depending on Neon, the neon breaksdown. C2 Discharges, Neon Recovers, The C2 starts charging again and so on and on. It Oscillates, probably in a Ramp Waveform. But do not use your Scope on this, you will regret it a lot. This is a live circuit and needs a special probe.

“Oh, i will put the probe it in 10M mode” will not do. The ground clip of the probe goes to Electrical Earth which is ‘connected’ to Neutral in the mains wiring. So you put the earth crocodile clip on the live point. There will be flashes and fireworks. So you need to isolate both terminals of scope. Please use your costly equipment with great care.

For the 1 Meg use two 470K in Series for 230V AC, that is safer. The circuit is live, so take precautions. The 0.47 Micro Farad can be increased if you want a slow flash. If the Mains 50/60 Hz Flicker is too much, the 1 uF can be made 2 uF, or use 4 – 1N4007 as a bridge rectifier.

From Schematics of delabs

User Feedback –

R1 of 4.7M and C2 of 0.47uF Works well at 230V AC. Try your own Combination. Less than 1M may damage Neon.