Monday 28 August 2017

Bor Yueh BY-201 Front Rack Review

Bor Yueh BY-201 Front Rack Review - Intro



I needed to fit a child seat to the rear of my bike, and wanted panniers for shopping too. So front rack is the route I went. This unlike a "lowrider" rack allows you to use full size rear panniers on the front of your bike.

A few years ago, people would have started talking about centre of gravity, but thanks to the marketing powers of firms like Salsa, "bike packing" sees luggage mounted all over bikes, typically very high up. I am not saying it is good, but it has become more trendy to have an unstably loaded bicycle. So I should not need to justify the whole COG thing.

Update: 06/09/2017

I have tested this rack with a 35kg load. Which consisted of 2 large panniers and a medium sized child. I travelled 10 miles with this load and bumped down curbs, and did some violent steering. All good. So a bit stronger than that 10kg mentioned on the website.



Smallish RAck - Full Size Panniers



Bor Yueh BY-201 Front Rack Review - Fitting


The rack comes with a selection of nuts and bolts for fitting, as well as plates for mounting, and what not. The only criticism here would be that the bolts are all screw driver type bolts and not allen key variants / jobbies.
No Caption - Self Explanatory 

You will require a hole in the fork crown (where the mudguards are bolted on) and also some forward facing rack mounts on the bottom of the forks. I doubt this would fit on to mudguard mounts, although there are some spacers provided which may get this to work.

Bor Yueh BY-201 Front Rack Review - In Use


I have owned one of these a few years ago. They are a good rack. Issues it for 2 or 3 years with no issues. So this is a 2nd purchase, which must count for something.

As mentioned in the intro this puts your luggage above 6" above low rider height. This really doesn't bother me in the slightest, and I can use any of the rear panniers I already have on the front of this bike.

Bor Yueh BY-201 Front Rack Review - Photos


View from Above - Lack of Allen Bolts is a Shame

Fixing are however, Sturdy

Mounting Point at Fork Crown 


PAM8610 Amplifier Review & Build

PAM8610 Amplifier Review & Build - Intro


I was very impressed with my 99p PAM8043 has enabled me to build a small portable speaker for just a few pounds.

Off the back of this success I thought I would build a more powerful portable speaker using a PAM8610, which costs . . . .  £1.99 so still a cheap project.

This is the board variant reviewed.


This more powerful board delivers 15W per channel, and runs on 12v (7v to 15v). I was hoping for more sound, which was delivered, but the quality of sound is far below that of the PAM8043.


PAM8610 Amplifier Review & Build - Power Supply


The 8610 will run on 7 x AA batteries (1300mah) for many hours at a moderate volume. A week's worth of morning and evening listening is achievable on one set of batteries, approx 12 hours. At full volume I would estimate 1 or 2 hours.

(2x15W) 30W / 12V would indicate a 2.5A current requirement, so if you choose a 12V AC adaptor for power probably best to go for 3A as a minimum.

The maximum voltage specified for this amplifier is 15V, the more volts supplies the greater the power output of the amplifier.

PAM8610 - More Volts = More Power (15 v Max)
I have tried this amplifier on  10.5V, 12V and 15V. I would say that after 12V there is little advantage to be had in terms of power output. When listening to music using headphone lead from iphone connected to amplifier, I can turn the volume to 90% running of 12V without distortion. At 15V I can turn it up to 70% without distortion.

So you may save the battery in you iphone a bit? But the extra volume is not worth the bother just stick with 12V. However, many SLA batteries will be near 15V fresh off the charge so it is useful to know that it runs well at this voltage.

It is interesting to note that many listing on ebay or elsewhere say that this amp will take 16V, the the specs it says 15V max. I will try it at 16V and see if it survives.

PAM8610 Amplifier Review & Build - Speakers


Many of the more complex boards using the PAM8610 require an 8 ohm speaker. But if you buy the basic board, then you can run a 4 ohm speaker . . .  the more complex boards do not really offer any advantages in terms of performance, although they are easier to use, with no soldering required (provided you have the right connectors!)



PAM8610 Amplifier Review & Build - Sound


The sound was a bit disappointing at first. It is a very mid tone heavy, to the point where it is harsh. Whilst the PAM8043, has a rich sound even when unfiltered this amplifier requires a low pass filter on the woofer, in order to make it listenable.

For example, without a low pass filter, you will require a graphic equaliser to try and remove some of the harsh mid range sound, and having tried this I can tell you it is not a very good option.

PAM8610 Amplifier Review & Build - My Set-Up


This project ended up looking a bit messy, because it had to be reworked so many times, attempting to get the right sound. In the end the addition of low pass filters was the breakthrough, that finished it off. I had tried stuffing the cabinet with wool to change sound, but this was unsuccessful.



The DIY low pass filter was easy to make. I just wish I had thought of it earlier. I had to make sure that the bass / mid range driver and the tweeter were fed separately through their respective filters.

Note size of PAM8610, very small. 

A close up of the amplifier and the wiring, between it and the speaker. The coil, shown below is the professionally made variant. Whilst above right, is a DIY effort that worked adequately.

Amplifier will happily sit on it own wiring, as it weighs next to nothing.
I did not worry about mounting the amplifier to the inside of the cabinet, as the the board is so light, it will sit happily suspended on its own wiring.




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Thorpy's Non-Technical Speaker Crossover Guide

Thorpy's Non-Technical Speaker Crossover Guide




Intro


There are plenty of guides around on the web showing how to build speaker crossovers.

However, I found most be a bit mathematical. You will need maths if you a building the perfect set of speakers, but for a functional set, you can use these rough instructions. They worked for me.

Crossovers are normally hidden inside a set of speakers and so unless you are building your own boom box, or set of speakers, you may never have seen one before.

I have taken some of the more simple advice on the web and dumbed it down still further, for those who want to see some pictures, and just have a go.

I have no clue how any of this works. But I have built a boom box, with the below components, some homemade / DIY, and it works. So I would urge you to have a go too.

What does a Crossover do?


If you look at most speakers they have two drivers, a tweeter for treble  (high pitch sound) and a larger driver for mid range and bass (low pitch sound).

What does a cross over do? Well it filters the sound and delivers high frequency sound only to the tweeter, and low frequency sound to the large driver.

Do you need a Crossover?


Sometimes no. Sometimes yes. Most speakers have some form of crossover. But how can you tell if you need one:

Example 1 - A crackly / distorted / snicky sounding tweeter may require a filter to get rid of the low pitch sound, that it is not designed to handle. In this case you would want to filter out low pitch sound, with a "high pass filter", which can be done with a capacitor (see below).

Example 2 - A harsh sounding mid / bass driver that is getting too much treble. In this case you would need to filter out the high pitch sound. This can be done with a "low pass filter", this is done with an induction loop.

What do you need to build a cross over?

Here is a picture of my setup. (I am sorry to say that the capacitor in this picture is covered with glue, so it is a little hard to see. But it is there! Click on the image to make it bigger)

Ugly but Functional


Ingredients - You will need:



  • Soldering Iron & Solder
  • Insulated Copper Wire 2 or 3 Meters
  • Bi-Polar Capacitor 40V +
  • Sticky Tape
  • Glue
  • Chunky Steel or Iron "Core for Inductor"*

*I used the spindle from a industrial motor, but you could use a bit of scaffold pipe, or a big bolt or a piece of broken round file. It has to be iron or steel.

Install a High Pass Filter (also called a "Bass Blocker")


A high pass filter is very easy to install, you will need a bi-polar capacitor.

Polarised or Bi-Polar


Now as a general rule you should choose a capacitor with a voltage above 40V, but the higher voltages will also work, although they offer no advantage. The "uf" can be anything you like, and will probably work OK. Search here.

Just solder the bi-polar capacitor between the positive amplifier output and the the positive terminal of the tweeter. The the tweeter should be "fed" power through the capacitor.

Top Tip: Do not look directly at the capacitor when you power up you system. It may explode if you have chosen the wrong voltage or type (polarised or bi-polar). If you look the other way the bits won't go in your eyes.

Install a Low Pass Filter (also called a "Treble Blocker)


To make your low pass filter (induction coil) take around 2 to 3 meters of door bell wire, or other single cored insulated wire, and wrap is around your chunky steel or iron core. Leave enough spare wire poking out so you have enough to solder it to where it needs to go.

An Induction Coil - Very Techncial

Power needs to be fed to you bass speaker through this coil. So you wire one end to the positive supply from the amplifier and the other to the positive terminal of the speaker. (Scroll back up to the labeled picture to see how)

Conclusion

As mentioned this will not get you a top notch speaker, but it will make a horrible sounding speaker sound OK. 

By example, before installing these DIY crossover coils, I had to have the equaliser on my iphone on bass booster, and the sound was still too harsh.

After installing I can switch the EQ off, and they sound well balanced, I used an induction coil (low pass filter) taken from a professionally made speaker for the left hand side, and my DIY induction coil (low pass filter) on the right hand side. I cannot tell any difference by listening between the speakers. So the homemade one is working it would seem. 

For Reference - This is a professional made induction coil. Note PAM8610 amplifier bottom Right.

For reference I am using a PAM8610 to run this portable speaker, from 7 x AA batteries. The speakers were taken from some low quality active speakers. Also I should point out that you can get a pretty good bluetooth speaker for £30 / $50. So do not spend too much money on this unless you are doing it for fun!

Inside my DIY Portable Speaker





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Wednesday 16 August 2017

Unstable / Surge Voltage for XL6009 Buck Convertor

Unstable / Surge Voltage for XL6009 Buck Convertor

I am new to electronics, and this small boost convertor has me baffled. It displays some weird behaviour. One sets the voltage using the small brass screw, but then if you watch and wait the voltage climbs from the set voltage, 5 Volts in my case up to 28v or higher. I have also observed the same behaviour when setting the boost converter to 10v.

This has resulted in me destroying a bluetooth amplifier, because after setting the voltage at 5V, and connecting the voltage climbed to 28v and killed the amplifier board (PAM8403).

I am powering the XL6009 board, with a headway 8ah LIfePO4 battery at 3.9V, which is rated for 100A output. So I do not think insufficient power is the problem.

If you have had any joy with this sort of thing O would appreciate some help.