Video Amplification/splitter from the internet - Page 1
Forum section: electronics / beginners

author: Halford
author_rank: Contributor
timestamp: December 24, 2015, 07:57:37 pm
content: Hi everyone and Merry Christmas,I wanted to build a small video splitter and saw online that I have to do an amplification to keep the video quality.I found this design(1) that used components that I already have and I made a schematic(2) and a board(3)end of story, I received the board, soldered everything, no video is coming out at the end. Do you see any error? thanksimages updated

author: bktemp
author_rank: Super Contributor
timestamp: December 24, 2015, 08:15:01 pm
content: There is no connection between R2/R3 and Q1, so Q1 gets no bias voltage.

author: Aodhan145
author_rank: Frequent Contributor
timestamp: December 24, 2015, 08:16:54 pm
content: Be more careful when laying the schematic out. You do not need junctions on the pins of all the components. Only place junctions where you need them when 3 or more wires join.

author: Halford
author_rank: Contributor
timestamp: December 24, 2015, 08:36:12 pm
content: Sorry, I uploaded the wrong eagle images.there is a junction indeed there, here they are:

author: lincoln
author_rank: Regular Contributor
timestamp: December 25, 2015, 03:46:42 am
content: Quote from: Halford on December 24, 2015, 08:36:12 pmok, but looking at the layout, R3 and R5 don't go any where....

author: PA0PBZ
author_rank: Super Contributor
timestamp: December 25, 2015, 11:21:54 am
content: Quote from: lincoln on December 25, 2015, 03:46:42 amNone of the grounds go anywhere, it's like it is following the schematics a bit too literally...

author: Halford
author_rank: Contributor
timestamp: December 25, 2015, 04:12:15 pm
content: Well... I'm following it litteraly as I'm a real noob... Got patient and will to explain or tell me where to look to understand it? Thanks anyway

author: LukeW
author_rank: Frequent Contributor
timestamp: December 25, 2015, 04:33:29 pm
content: Could you post photos of the physical board you've constructed?I assume there's actually a ground pour connected to all the ground pins.

author: PA0PBZ
author_rank: Super Contributor
timestamp: December 25, 2015, 07:16:07 pm
content: Quote from: LukeW on December 25, 2015, 04:33:29 pmWhere would it be, on the third layer?

author: PA0PBZ
author_rank: Super Contributor
timestamp: December 25, 2015, 07:17:03 pm
content: Quote from: Halford on December 25, 2015, 04:12:15 pmAll the points marked GND should be connected together.(That is why they all have the same name)

author: Halford
author_rank: Contributor
timestamp: December 25, 2015, 07:19:43 pm
content: all ground are connected.here is a ratsnest from eagle, and the top and lower image from OSHpark... I was so sure it would work, that I made it print as final online. (probably better then a picture of the circuit)Thanks for looking

author: Halford
author_rank: Contributor
timestamp: December 25, 2015, 07:26:08 pm
content: I think I found my issue.. bad layout... I feel so idiot.the 12V input has his gnd not connected to the rest.... I guess this would sabotage the whole circuit.. I feel so stupid.

author: PA0PBZ
author_rank: Super Contributor
timestamp: December 25, 2015, 07:27:58 pm
content: Quote from: Halford on December 25, 2015, 07:19:43 pmAlright, that looks promising!Can you measure the DC voltages on the transistors pins and post them?

author: lincoln
author_rank: Regular Contributor
timestamp: December 25, 2015, 07:44:39 pm
content: Quote from: Halford on December 25, 2015, 07:26:08 pmIts quite all right, nothing a bit of bodge wire will not fix!

author: PA0PBZ
author_rank: Super Contributor
timestamp: December 25, 2015, 07:49:02 pm
content: Quote from: Halford on December 25, 2015, 07:26:08 pmAh yes, floating fills... Been there, done that. Heat your iron and let us know

author: LukeW
author_rank: Frequent Contributor
timestamp: December 26, 2015, 09:29:51 am
content: Did you run an ERC?

author: Halford
author_rank: Contributor
timestamp: December 26, 2015, 01:05:35 pm
content: Thanks guys!It works perfectly!Thank you for taking the time to look after my post!Have a great day!Hal.