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Wednesday, February 27, 2019

24V and 25V Power Supply with 2A Current

I am looking for a 25V Power Supply with 2A current for my Application. A regulated supply.

TA - US

Here is a simple to build regulated power supply. The two diodes are to boost the 24V to 25V DC. It uses regulator 7824 and TIP2955 PNP Transistor to boost current.

24V and 25V Power Supply with 2A Current

delabs



Thanks alot! Do you know of a good transformer manufacturer that has the one you specify? Also, is that "100V 3A" at the bridge the rating on the diodes? Also does the transistor circuit increase the voltage to the regulator so that it is 3 or more volts above the regulating voltage? Lastly, is your ground reference on the gnd of the regulator?

Wait, one more....this is + or - 25 volts correct?
Thanks alot!

TA - US



1. choose a transformer with a close match of what is available.

2."100V 3A" at the bridge is the minimum diode rating also(or use 4 x 1N5408). "100V 3A" is also minimum bridge rating use a close match.

3.to make a bridge with 4 diodes refer my other circuits, there are many.

4. 22V AC leads to around 30V unrectified DC which is good, if the 30V becomes more, the heatsink needs to be very big.

5. the ground of regulator is lifted by (0.7*2) by 2 diodes to provide 1 V above 24V, as 25V regulator does not exist. the power supply 'neg' can be grounded or earthed,

6. the supply is a+25 V from ground or negative, but things are only relative.

7.if you need a dual supply 3 terminal , that is ground +25 and -25 then for -25 one more circuit using 7924 and tip3055(npn) has to be made.

8. use any high current pnp transistor (5A) you have put a heatsink with heatsink compound.

delabs

Monday, February 25, 2019

UPS and Inverter Schematics

Do you perhaps have an inverter schematic for a sinewave inverter or stepped squarewave using the SG3525 chip.

I'm also interested in connecting the inverter to the grid via a solar panel. I hope to reduce my electricty bill by pumping power into my 220v system. Do you perhaps have circuits to synchronise the inverter to the 50hz main.

PT - EU


Nice to get your email. .. Have you seen the circuits in my page....

Power and Energy Schematics

Switch fast from mains to inverter. The inverter is always on with the battery charged by the mains.

UPS and Inverter Schematics

The mains load is of two types

lighting low current 5A ??  and  heating high current 20A??

You should isolate both of them, the UPS is only for lighting. For heating you need a very big UPS, solar will not help, oil might.

delabs


I want to build a home UPS System. Uninterrupted power supply for computers and with Solar Cell Integration. I need some Schematics..

JK - US


You have to design and develop these equipment, just a circuit or instructions will help you learn but you cannot make a robust product. Anyway have a look at these applications to learn ..

Sine wave Inverter 800VA

Learn about UPS here  UPS Power Inverter and DC to AC

delabs

Thursday, February 21, 2019

Making Coils and Transformers

Message - Can we make Coils and small transformers at home. I have copper wire and some lamination in my stores. - 2005

IJ - AF


Making Transformers with good isolation and safety is a task for a firm and a home user must learn those skills by working in a winding company first.

As this is a general question many ask i am posting some educational pages. here...Coils and Transformers - Magnetics, Inductors, Chokes, Ferrites - Iron and Copper, Electromagnetism, Alloys, Insulators

Making Coils and Transformers

We have low frequency and high frequency transformers and coils in power electronics and electrical engineering. Then we have signal coils and transformers used in communications.

Low frequency transformers are made of a core of iron alloys in the form of insulated laminates to reduce hysteresis and eddy current losses. The copper wire insulated by a thin insulating enamel coat is used to wind the primary and secondary coils.

Coils and Transformers for SMPS, In Switching Power supplies and RF Circuits, the coils and transformers have many types of cores. Ferrites, Powder Iron, Air and others.

Producing wound components

This page provides practical guidance for students, staff and researchers at this University who need to wind their own inductors, transformers or solenoids. The types of wound components available, and their applications, are so varied that only general guidelines can be provided.

Compact Fluorescent Lamp (CFL)

Compact fluorescent lamps have some benefits in comparison with classic light bulbs. It is lower power consumption (to 80%) and much longer lifetime (5 to 15 times). Disadvantages are longer starts mainly at more expensive types, impossibility to use darker and price.

Practical transformer winding

In the good old times it was a matter of fact that every electronic hobbyist or technician would wind himself any power transformers he needed, and rewind any that burned out. Unfortunately, nowadays transformer winding is fast becoming a lost art, and I have seen many people despair about where to find some very specific transformer, or pull their hair out about the cost of having one professionally wound to specifications.

Winding Coils - Ham Radio

I used to view the inductors of RF circuits in books and magazines as problematic, often shunning any radio circuit having coils which are difficult to find . RF inductors of the correct value, unlike standard components, are not easy to buy, if at all. However, there are some great radio circuits around and it's a pity not to be able to reproduce them just because you normally can't acquire their coils off-the shelf.

delabs

Tuesday, January 29, 2019

Mixed Signal Grounding Method

How do we interface Analog and Digital Blocks. The earlier post explains ground connections that are radiating from supply but does not show Analog and Digital Blocks Interface.



Analog Blocks have Opamps, Analog Mux, A/D Convertors and D/A Convertors. Some microcontrollers have built in A/D and D/A then you have to use the separate ground pins they provide. The implementation remains the same.

Mixed Signal Grounding Method

The diagram above is self explanatory. There are mainly types of return ground paths... to the power supply ground

Pulsing Ground - From Digital circuits that are switching in MHz speeds.
High Current Ground - From Interface or Power, LED, Motor Circuits.
Clean Signal Ground - From Analog Signal Conditioning and Mixed Signal.

Use proper decoupling caps at every chip and every functional circuit block. Have a ground plane that doubles up as a shield in on or more layers of PCB. In RF circuits you could use two ground planes on two layers of pcb and signal tracks in between.

Wednesday, January 16, 2019

LM3914 Circuit Ground Connections

I am about to build the circuit that you have here: - Millivolt Meter - Bargraph

I am pretty sure that I understand all of it, except for the symbols that you have at the grounds which are little triangles with the letter F next to them. Please excuse my ignorance, but what does that mean? Is that the ground from the tested millivolt source?

MK


One Ground carries the LED Currents and that track has to be thick and go directly to the Voltage Regulator 7805 which provides 5V supply. If this track is looped with the signal ground, millivolts of error may occur in reading and if tracks are thin it may lead to oscillations.

LM3914 Circuit Ground Connections

We have a High Gain Amp  in this circuit that will amplify even these small jumps in mV due to track Resistance in ground loops.

Analog Ground, Digital Ground, Supply Ground, RF Ground and Earthing have to be carefully designed to get accurate performance. PCB Autorouting may ignore these subtle requirements.

Monday, January 14, 2019

ICL7135 PCB Layout Method

I have design a PCB layout for a 4.5 digit voltmeter using the ICL7135 chip, and i have problems with the analog and digital ground. Do you know if somebody have make a PCB for this chip?

I have seen in your schematic a superb circuit- del2003.sch, ICL7135 based auto ranging DVM. Do you know if the PCB layout is avalaible?

I will appreciate to have some help or if someone can send me the PCB layout for the del2003.sch.
Thanking you in advance,

Mail from RL


I am not able to locate my PCB Layouts, but to study about analog and digital grounds for this chip and pcb layout see this Service Manual i found online.

delabs Notes -  Discuss Topic here EE Forum - Analog Ground

Digital Grounds have Switching Noise or Pulses, Interface Grounds have higher currents. Sensor  Low inputs that are not isolated may have potentials and may lift the system ground and also pose hazard. Electrical Earthing and System Grounding are also different things.

Analog Ground and Digital Ground

Keep the analog and digital current return paths separated.  Remember all tracks and wires are resistors and conductors too. connectors have contact resistance. soldered joints (and connectors) have thermometric EMF. Looping Tracks is wrong Radiating tracks is right.

Read this PDF too Grounding in mixed-signal systems demystified, Part 1
Undoubtedly, grounding is one of the most discussed subjects in system design. Though the basic concepts are relatively simple, the implementation is difficult. For linear systems, the ground is the reference against which the signal is based; and, unfortunately,

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