Buying cheap electronics at Ebay: Part 2

This post lists some basic components for creating projects that require soldering and explains how to buy them for cheap prices at eBay.


Introduction

This post covers some components that we can buy on eBay and allow us to solder a circuit, instead of just mounting it on a breadboard. This leads to a more robust solution and less problems related to poor contacts.

We are not analyzing soldering irons since they come in big packages and, many times, they are stopped in customs and we need to pay taxes to get them. So, before looking for a soldering iron on eBay, it’s better to check local stores first since we may get some acceptable prices.

 

Perfboards

Breadboards are a great tool for building electronic prototypes without the need for soldering, also allowing for an easy reuse of components. Nevertheless, when the designs start to become more complex, it’s generally a good idea to move to some solution that involves soldering. This way, we avoid problems related to poor contacts or noise due to  using long wires.

Since building a custom PCB is considerably expensive, one interesting solution is using perfboards, as shown in figure 1. Perfboards are kind of a middle solution between the PCB and the breadboard. Although we need to solder the components to the board, as we would do in a PCB, we have the freedom to solder the connections between the components.

Perfboard

Figure 1 – Perfboards. Taken from [1].

It’s important to say that the distances between the holes of the board are typically standard, as in the case of the breadboards, making it easy to fit through hole integrated circuits and other components.

We can find many types of these boards, with different areas for soldering, for less than 1 euro at eBay.

 

Headers

Sometimes, we want to have the freedom to connect and disconnect components from our main circuit. So, to avoid the need for soldering and unsoldering, we can add some connector headers to our perfboard.

We can find them at eBay in different formats and packs, from single row connectors to multi row connectors.

Single row connectors are easier to use since we can cut them as we need, and we can solder multiple rows side by side with them. Just as a note, the spacing between female pins is very short and with regular tools we need to break a pin when we cut the row.

The price depends a lot on the number of connectors per row and on the number of rows. But, as an example, a pack of 10 female, single row pins, with 40 connectors costs about 1 euro. Figure 2 shows this type of female headers.

Female breadboard headers.jpg

Figure 2 – Female connectors for perfboards. Taken from [2].

A pack of 10 male, single row pins, with 40 connectors can be bought for less than 1 euro. Figure 3 shows this component.

Male breadboard headers.jpg

Figure 3 – Male connectors for perfboards. Taken from [3].

This components are sold with standard spacing between pins, making them easy to fit in perfboard holes.

 

Jumper wires

When using the perfboards described before, it’s common that we have to connect distant components. To avoid long solder lines, using wires to directly connect the components is a good solution.

The straightforward approach consists on buying some copper wire, cut it to the exact measure needed and solder the tips to the two points we want to connect. Nevertheless, we can also use some tinned jumper wires, as shown in figure 4.

Thinned breadboard jumper

Figure 4 – Tinned jumper wires. Taken from [4].

These wires have a plastic isolation and since their tips are tinned, they are very easy to solder. Although they are thin, they have a fairly decent robustness, suitable for these kind of prototypes. Nevertheless, it’s not easy to cut them for custom sizes and then remove the plastic cover to expose the conductor, due to their small width.

One interesting thing is that these jumpers are actually advertised for breadboard use, but they are not a good choice for such use since the exposed metallic tips are not long and solid enough for breadboard holes.

They can be bought at eBay in kits of 100 for less than 1 euro.

 

Bolts and nuts

As can be seen by figure 1, perforboards don’t have any kind of lateral support. So, the soldered part will be in direct contact with surfaces, which can lead to the damaging of connections over time.

Nevertheless, typical perfboards have four holes, one in each corner, where we can easily fit a M2 size bolt. After that, we just need to apply a nut to each bolt and we end up with a pretty solid support, avoiding direct contact of the solder with surfaces.

We can find packs of M2 bolts and nuts at eBay between 2 and 4 euros, as can be seen here. The value will depend much on the length of the bolt.

Note: Although this may seem a high price for some readers who can buy them at much better prices at local stores, I’ve shared the link because here, in Portugal, I tried 4 different stores and none had M2 size bolts.

 

Final notes

To finish this post, I would like to show an example of a circuit I created and soldered using the components mentioned above. This circuit is shown in figure 5 and corresponds to one of the earliest prototypes of a Smart Medication Dispenser I created.

IMG_20150627_144731

Figure 5 – Example of a circuit soldered in a perfboard.

As can be seen, there’s a M2 bolt on the right side, which was used with other three, not visible here, to create a support for the perfboard and avoid damaging the soldered area. On the bottom, we can see some salient wires, which are jumpers of the type shown in figure 4. There are also some female connectors, which allow do connect and disconnect components without the need for soldering and unsoldering.

 

Related posts

Buying cheap electronic at eBay part 1 – Creating a basic electronics prototyping kit.

 

References

[1] http://www.ebay.com/itm/10pcs-9-x-15-cm-DIY-Prototype-Paper-PCB-Universal-Prototyping-Circuit-Board-NEW-/191923755368?hash=item2caf8c1968:g:HKYAAOSw14xXEvBA

[2] http://www.ebay.com/itm/10pcs-1×40-Pin-Single-Row-2-54mm-Straight-Female-Header-NEW-/272017852547?hash=item3f55870883:g:hWcAAOSw9mFWIIoL

[3] http://www.ebay.com/itm/10Pcs-40-Pin-2-54mm-Single-Row-Straight-Male-Pin-Header-Connector-Strip-/301997673088?hash=item465076ca80:g:dcYAAOSwukdXcNfj

[4] http://www.ebay.com/itm/100pcs-Solderless-Breadboard-Protoboard-Motherboard-Jumper-Cable-Wire-Tinned-6cm-/400991801136?hash=item5d5cf94f30:g:vl0AAOSw4SlV7rGw

Advertisements
This entry was posted in Electronics and tagged , , , , , . Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s