delabs Circuits

Thursday, September 28, 2017

Mains Stability and Supply Regulation

I have problem with my power supply... . The power supply uses LM317 and TIP2955 and the unstable AC net here causes the output to drop sometimes below 5V. The normally output is 13,5V. I like to look at your schematics to improve my power supply.

Mail from WV

See some circuits here ...

See the Insides of a DIY Ham Radio Power Supply

DIY Ham Radio Power Supply

You have to ensure at least a min of 15V AC to the Bridge or diodes on transformer. Only if a DC of around min 17V is available at input DC of 13.5 can be managed by this circuit. This circuit will not boost a voltage from a lower value for that you need Switching Boost Supplies.

Use AC Voltage Stabilizers or ServoStabilizers to maintain a stable AC Supply.

WorkBench Dual Power Supply
LM317 - Simple Workbench Dual Power Supply

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.....I like to compare with my schematics from our power supply. We have something very strange.. the backup battery takes over and don't cause a voltage drop when I disconnect power supply from 220V AC lines.. but the backup battery can not anticipate the disturbances in the 220V AC lines and gives a very short power drop at the output..

We have sometimes very short power drops at the output of the power supply.. Do you have any idea what is wrong? The transformer is 16V AC 3A
Reply from WV

You can double the size of filter caps at input. use something like 10,000uF, if you draw 3A a 10000uf across the input rectifier may help. Or you have to use a battery of 12V after the LM317. So that the battery can supply the short outages.
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But that is exactly my problem, we have a large battery after the power supply of 13,5V 5,5Ah, but it doesn't help to avoid the powerdips after the power supply..
Reply from WV

I feel you have a ground loop problem, The wires to the battery seem thin. I feel the potential across a ground wire must be lifting up when mains fluctuates.

The PCB ground plane may be thin or absent, check all ground and supply wires. Make all supply wires and Tracks thick and radiate from a center copper lug reference. Both positive, negative and ground tracks reinforce with lead or copper braids. Use decoupling caps at every stage.

delabs

Wednesday, September 27, 2017

BioMedical Circuits and Electronics

Circuit: biomedical circuits email: AA
Message: I'm a student in technical studies college, and i need to study medical circuits for my Graduation.

letter from - AA

Look here ...

Biomedical Circuits Technical Committee - The goal of the Biomedical Circuits and Systems (BIOCAS) Technical Committee is to foster research, development, education and industrial dissemination of knowledge relating to the emerging field of microelectronics and nanotechnology in biological and medical applications.

BioMedical  Electronics

BioMedical  Electronics

Bioelectric recordings - The instrumentation amplifier circuit normally used in bioelectric recordings is improved for measurements under difficult circumstances. Another application is a low-cost 64 channel amplifier for multichannel ECG recordings. The third application is a device that can be added to bioelectric measurement systems and will provide a major reduction in interference.

Neurostimulation of the spinal cord - The wireless system includes a wearable recording module, a wearable stimulation module and a transceiver connected to a computer for real-time and off-line data processing, display and storage.

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Friday, September 22, 2017

8254 Programmable Interval Timer Counter

I am doing final year b.tech, i am doing project on 8254 controller. please can u give me information about it. -thanks in advance.

from SA 


8254 Timer and Counter Board - This is a photo of a general purpose timer/counter card you can wirewrap in a weekend. It plugs into your PC's ISA bus just like a sound or modem card. It gives high-resolution timing (microseconds). Because of its programmablity, it is very powerful and flexible.

8254 Programmable Interval Timer Counter

C8254 Programmable Timer/Counter Core - The C8254 core implements a high performance programmable interval timer/counter device, which is designed to solve the common timing control problems in microcomputer system design

Using the 8254 Timer-Counter - Understanding the role of the system’s 8254 programmable Interval-Timer/Counter.

8254 Timer Datasheet - pdf  - The Intel 8254 is a counter/timer device designed to solve the common timing control problems in microcomputer system design. It provides three independent 16-bit counters, each capable of handling clock inputs up to 10 MHz.

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