delabs Circuits

Friday, July 21, 2017

Continuity Tester

Question - i want a continuity tester circuit or get one.

mail by RB

Here are some pages that might help

Simple Component and Continuity Tester - This simple project may be used for testing components, as well as checking circuit board tracks, wires and connections for continuity (conduction). It tries to pass a small current through the item being tested and the LED will light brightly, dimly or not at all according to the resistance of the item.

POPTRONICS Continuity Tester - This is another invaluable piece of test equipment for digital work. It has been designed by us to cater for a particular application . . . servicing digital projects sent in for repair. 

Continuity Tester, Smart - A tester by Tony Van Roon. This uses a 741 opamp and works off a dual supply and hence rather complex but more accurate. This may need some design changes too.

Silicon Chip Online - A Programmable Continuity Tester - Let's face it, almost every analog and digital multimeter does have built-in capabilities for testing continuity. However, this function is somewhat limited.

It would be a good idea to buy one like this

Continuity Tester CT6101

Heavy-Duty Continuity Tester CT6101- The Continuity Tester is very easy to use and is used to test for breaks in non-energized wires or cords. Continuity has a bright 360 degree visual indicator located near the tip along with a flexible lead for ease of use.

Thursday, July 20, 2017

Simple Battery Characterizer

I was reading about some IC's from Maxim/ Dallas saying " Simple battery characterizer" for plotting a charging/ discharging cycles & graphs are available on computer for study I want to plot an extensive data of these batteries.

From MO

This circuit is a battery characterizer that applies a fixed load to a charged NiCad or NiMH cell and measures milliamp-hour capacity as it discharges.

PIC-based circuit example from Westford MicroSystems - Battery Characterizer that determines milliamp

Simple Characterization Circuit

Simple Characterization Circuit for Rechargeable AA Cells - Maxim.

Abstract: This characterization circuit, plus a PC and some software, accurately measures the full discharge cycle for a rechargeable AA cell. Cell capacity and output resistance can easily be determined from the curve resulting from these measurements. 

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Friday, July 14, 2017

Desoldering Methods

Dear Solderman, i hope you know how to dessolder a wave soldered component from a board. There is problem because the pins are two face soldered. - thanks

mail from JS

Sending a few sites, read them all and then tell me.

Desoldering - Wiki

A component with one or two connections to the PCB can usually be removed by heating one joint, pulling out an end of the component while the solder is molten (bending the other lead to do so), and repeating for the second joint. Solder filling the hole can be removed with a pump or with a pointed object made of a material which solder does not wet, such as stainless steel or wood.

Desoldering Methods

How to Desolder

One of the most frustrating parts of building electronic circuits is getting something wrong. For a board that should take ten minutes to put together, you could spend an hour just trying to fix a component that you got backwards. Sadly, desoldering it’s not as easy as soldering in reverse.

Desoldering requires two main things: a soldering iron and a device to remove solder. Soldering irons are the heat source used to melt solder. Irons of the 15W to 30W range are good for most electronics/printed circuit board work.

Desoldering THM and SMT

Desoldering is a topic that no one seems to get to excited about until the time comes when people discover that a lot of damage is being done during this operation.

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