Monthly Archives: October 2008

What is a heatsink?

When current flows through a resistor, part of the electrical energy is converted into heat that gets dissipated into the surroundings. If the heat generated is not quickly removed, it can permanently damage the electronic circuit. Heatsinks are devices that are capable of removing the heat from electronic devices and speedily dissipate it into surroundings.

Heatsinks can be passive or active devices. Passive heat sinks consist of fins made generally

Voltage Regulator in a Heatsink

Voltage Regulator in a Heatsink

of aluminum that provide a large surface area for heat dissipation. Active devices in addition have fans that circulate the air around the sink for faster removal of heat. The heat dissipation in a heatsink takes place principally through convection either natural or forced.

Heat transferred through convection is proportional to the temperature difference between the heatsink and the surroundings. The constant of proportionality is called convection coefficient. Mathematically, q = h x A x ∆t, where q is the heat dissipated by convection, h is the convection heat transfer coefficient, A is surface area and ∆t is the temperature difference between the heat sink and the surroundings. The coefficient h is a function of velocity of air circulating around the heatsink among other things. Thus higher the speed of air circulating around the heatsink faster is the heat dissipation.

Heatsinks are widely used for cooling electronic devices and the surrounding circuit like the CPU in a computer. With the need to make electronic devices more compact and powerful, the need to make high capacity heatsinks is increasing. Modern heatsinks are manufactured by extrusion, die casting, cold forging etc. Heat pipes have been used in heatsinks as they are lighter and more efficient compared to solid pipes of same size. Anodized aluminum is the most common material used in making heatsinks, although copper, silver and even gold have been used.

Custom Tube Amp in Time for Halloween

Steve W. from Peterborough, Ontario, Canada sent me some new pictures of his latest projects.

He built this particular amp for himself. It’s a 40 Watt per channel 807 that used 8 of our 470uF 400V Electrolytic Capacitors .

The finish is blue perl clear coat – that finish is perfection!

We’ll be posting more of Steve’s custom tube amps over the next couple of days.

As always – great job, Steve!

Halloween Amp

Halloween Amp

Halloween Amp2

Halloween Amp

Halloween Amp3

Halloween Amp

Op Amps – Then and Now

Op Amps – Then and Now

Op amp is the commonly used name for operational amplifiers, which are widely used electronic components. Op amps are often seen on many surface equipment designs and logging tools.

The name ‘operational amplifier’ comes from the use of such high gain amps in performing mathematical operations for analog computer operations and is said to have been coined in 1947. A lot of study was done in the field and the initial operational amplifiers, based on vacuum tubes, were a result of the research done in Bell labs. By 1960’s, vacuum tube op amps had given way to solid state devices and hybrid operational amplifiers were entering the scene.

The first IC operational amplifier was developed in 1963 by Bob Widlar and was called Fairchild µA702. It was not a success because of a number of bugs. But Widlar’s next design, which was the µA709, was hailed as milestone in design. A number of designs followed including the very popular µA741. A number of precision op amps like OP7, OP27 and OP37 are commonly used in logging electronics.

In the initial days, these electronic components were based on NPN bipolar process and because of the slow PNP transistors of the time; the speed of the amps was limited. The LM118/218/318 model tried to solve the problem but did not meet with much success. The only fast IC op amps were the ones owned by Harris, the HA2500 as well as the HA2600, and were quite popular despite their high cost.

FET input operational amplifiers though highly advantageous in downhole tool applications, did not enter the scene due to engineering problems. However with the introduction of the ion implantation process in 1974, their manufacture became possible and the LF155/156/157 series was introduced by National Semiconductor, and OP15, OP16, and OP17 by PMI. The TL06x, TL07x, and TL08x models introduced by Texas Instruments (TI) in 1978 went on to become industry standards.

The CA3130 employing a P-channel MOS input with a CMOS output, set the stage for CA3140 having a MOSFET input and a bipolar output which caught the eye of many logging tool companies. This model has many advantages including good bandwidth and military temperature range, and continues to be used and manufactured even now.

Tact Switch – SKPFABA010

We’ve been selling a lot of this one particular switch – it’s called a long travel tact switch; manufactured by ALPS.

Here are some of the features of this switch:
— Dimensions: 8mm x 8mm
— Suitable for automotive applications due to its high operational force
— Malfunctions are prevented due to it having a longer travel than most conventional tact switches
— Easily mounted on a PC board with snap in leads
— Some of the output terminals can be used as jumper leads which makes the circuit arrangement simple

Here are some other uses:
— automotive electronic equipment
— communication devices
— measuring instruments

These switches are available right now – they have been priced lower than any other distributors.

Be sure to check them out next time you need a 12V tact switch!

Desoldering – Why is it Necessary and How is it Done?

Soldered joints, if improperly done, may need to be ‘desoldered’ or the solder removed in order to resolder them. A poorly soldered joint can result in failure of the electrical circuit over a period of time. This can happen for a number of reasons. Low quality solder or failure to properly clean the surface before soldering or even lack of proper technique and corrosion of the joint due to leftover flux, movement (shake) of the joint before the solder has cooled may all cause a poor soldered joint.

There are other reasons you might need to desolder a joint. Desoldering and resoldering may also be required in order to replace a defective electronic component or if you are troubleshooting an electrical circuit.

One common method of desoldering is to use a desoldering pump which is a vacuum pump similar in operation to a bicycle pump in reverse. The spring loaded plunger breaks the solder and gets sucked away by the pump. Repeated operation of the pump may be required in order to completely desolder a joint, or you can also use the solder pump to take up the bulk of the flowing solder and finish up the job with solder wick. Either way works – the solder wick is more expenisve so you may want to use both if you have a large job. Be careful – the pump should be operated carefully so that no damage the PCB or the electronic components occurs.


A solder wick or braid is an alternative to desoldering pumps. Here the copper wick is placed over the joint and the solder is melted by means of soldering iron. The solder gradually flows into the wick and hence gets removed. The wick must be removed from the PCB before it cools down as otherwise it may damage the board.