But but but... I can't have fun with that :<

Anyways I'm thinking about adding a LC filter rather than my single capacitor that is filtering the power lines.

Oh they are very fun.

Added some now stuff to the PCB because of the increased size and cheap prices of this fab house.

1) External battery input, Power selector switch (battery or USB), Power source indicator LED. The purpose for the external battery is for noise reduction (batteries have way less noise than USB), as well as for on the go support with phones and tablets that can not provide the power needed to operate this hardware.
2) LC filter based off an inductor and capacitor (which replaced the single capacitor filter). The inductor in series allows DC current to pass while limiting AC current/noise, while the capacitor in parallel takes the excess AC current and brings it directly to ground.
3) A zenner diode for over voltage protection. When the zenner does not reach its avalanche point it provides a hold voltage, but when it reaches the point it changes and allows current to flow to ground.
4) A PTC fuse. Under normal hold conditions the fuse forwards the current throughout the circuit, but when a short happens the current increases which heats up the fuse. As the fuse heats up it changes its carbon infused crystal makeup which increases its resistance limiting the amount of current that passes. The problem with these is that even though the fuse is in a tripped state it still allows current through.


The parts/traces are in temporary placement just for the sake of getting it on the PCB. I think I may remove the zenner diode and PTC fuse because they really are not needed and causes unnecessary voltage drop. The USB on a host usually already has PTC fuses to prevent damage to the host so that would also protect this hardware, and there should also be over voltage protection. This hardware will not create a short either nor change its voltage usage and all hardware *SHOULD* be securely mounted inside the enclosure so that shorts will not happen.

Anyways here's a photo. Pretty sure I'm going to remove the excess components and for sure clean up the traces around the LC filter.

I am still looking for shit to add to make up for the size of this PCB. Only real option left is cool hacker graphics.



This post was edited by AbDuCt on Sep 3 2014 11:26pm

Got some more toys and still waiting for more.

Firstly I received my low noise amplifier. The thing is tiny, but that is a plus for me becuase I want to make my radio setup as small as possible. The LNA, unlike normal amplifiers which amplify everything including noise, tries to reduce the noise floor allowing weaker signals to be heard more clearly.



Next I bought some more coax rg316 pigtails. 2 with F -> SMA male connectors, 2 with SMA male -> SMA male connectors, and 2 with SMA male -> MCX male. These will allow me to hook up all my hardware together.

My HF up converter still hasn't arrived but I believe it will be here soon. I also found a project box that will work as a temporary box to house the hardware. It is a old chocolate tin with removable lid. The metal of this tin will help block outside noise from entering the hardware. Inside the tin will be the software defined radio, the power filter, the LNA, and the up converter. Each of which will have a radio frequency blocking copper can mounted on top so that the hardware does interfere with each other inside the tin can.

The Power filter PCB is almost done, I changed it a bit more moving the LC filter around to create cleaner traces on the PCB. I might tweak the filter a bit more because I don't think I need two inductors for such a project. After I fixed it and moved all the components so that it evenly uses the entire PCB I will send it off to be fabbed. Most likely this will happen Sunday or Monday.

Here's a screen of the current PCB:



It will be a month before I can actually put this project together as the fab process takes a while and the pigtails from china will take many weeks to get here, but once I do I will post before and after screenshots or videos of how what I did reduced the noise floor and cleaned up all the signals to make this dinky little SDR into a pretty good radio. So far I have invested a little under 100$ for hardware which can be moved around to other projects of mine.

The LNA cost 35$, the up converter cost 45$ and the pigtails cost 19$. Parts I have gotten for free so far are the chocolate tin project box, the molex connectors for the pcb, and a remote usb batter/power adapter which may or may not be used. If you're interested in listening to radio this project is a good start as its plenty cheap as for what normal radio gear costs. Also with a little hardware hacking you can make this radio receive from 100khz to up to 25ghz with up converters/down converters. This covers many bands such as CB, public safety, aircraft, marine, amateur operators, cell phones, emergency services, trains, satellites, CW (morse), digital slow scan tv, fsk/psk digital communications, provoice encrypted voice traffic (cops mainly), police trunking, and a bunch of other shit I forgot.

Anyways yar.

Last update on this project for a while. Here is the final pcb using oshpark's gerber file rendering engine to show off the PCB. I have to wait for my molex connectors to arrive so I can fit test onto a piece of paper before sending this off to iteadstudio for manufacturing.

Here is the final rendered PCB as per oshparks engine:



This post was edited by AbDuCt on Sep 7 2014 12:38am

Why not dirtypcbs ?

That is cool that you can get custom PCBs made. How much is it going to set you back?

Never heard of them. What are their turn around times and prices like? itead is 30 days turnaround but its 25$ for 10 PCBs 5cm X 10cm.



About 25$ for 10 PCBs for 5cm by 10cm which is fairly cheap compared to other fab houses; I also get to choose the color of the PCB. Fritzing wants 38$ for one PCB, and oshpark wants like 30$ for 3 PCB's.

Sheesh. Way over priced in comparison.

http://dirtypcbs.com/index.php

10 each 5x5cm PCBs $14 • 10 each 10x10cm PCBs $25
10 pieces, 2 layers, 100% e-test, any color, worldwide shipping included. No Bull...



Fairly typical, pricing is excellent.