Re: Hedghog standards converter
 

Thanks. If you mean 74dBuV (5mV), that's a little less than the Aurora's 76dBuV (6.3mV) but still a good level to have.

Steve

Re: Hedghog standards converter
 

Hi Frank,
I've decided to take the plunge & have a go at building one of these. I'm sure it would be far more sensible to buy a built one from Stephen but where's the fun in sensible? ;D

There are a couple of anomalies in the component list. These are C37 & C41. Both are shown as 10nf on the circuit but the part number on the component list shows that for 10 mfd.

Looking at the circuit, C37 couples the video signal into the modulator IC. Should both of these components be 10n or 10mfd?

Many thanks
Nick

Re: Hedghog standards converter
 

C37 & C41 are both 10nF

Re: Hedghog standards converter
 

Freya,

I think those Hedghog converters look really great (very nice job). Can you give a rough indication of the price of a completed unit ?

Re: Hedghog standards converter
 

Only price by PM, which I will send.

Re: Hedghog standards converter
 

Many thanks!

So far, Farnell can supply almost everything and in small quantities too. SMD resistors & caps can be ordered in 10's for not much money. They can supply all the semiconductors including the IC's except the two modulator chips and the FPGA board.
I'm still working through the component list but so far, so good!

Strangely, Farnell list all the LM7805 variants as 'no longer made'! which was a surprise. I should have some somewhere though. The one component I can do from stock is the 1N4001 as it's a real one with legs!

When it comes to programming the FPGA, will the Altera software run under Linux? I don't have access to a Windows machine- in fact the last Windows I used was W98! I'm on shaky ground anyway when it comes to using computers but I do have a PC running a current version of Lubuntu.

Many thanks
Nick

Re: Hedghog standards converter
 

I have not looked at this project, so if the 7805 is used in some very odd way that makes the exact part critical then I apologise.


It's just a 5V, 1A fixed voltage regulator, surely. Farnell do plenty of them from other manufacturers. Do a search for '7805' on that site, for example :


https://uk.farnell.com/texas-instrum...323602?st=7805

Re: Hedghog standards converter
 

Yes, of course,you are quite correct- it was just me being stupid! :dunce: I never thought of looking for one with a different prefix! I must have been playing with valve TV's for too long!
This project is at the other extreme:- I can't even see half the components!

All the best
Nick

Re: Hedghog standards converter
 

Hi Nick
There was mistakes on the original documents on the web page I believe they have all been corrected now. So any one starting the project should download a fresh copy of them.
If any mistakes are found on a fresh copy please let me know.

As Tony has said and 5V 1A linear regulator with the correct pin layout should be fine.

There is a Linux version of the Altera software but I have not tried it. I used the windows version.

Hi Steve
Hedghog uses two MC44BS373CA modulators as does the Aurora. So the output should be fairly close there may be differences in the way that the outputs from the two modulators are combined which could account for any difference in level.

Frank

Re: Hedghog standards converter
 

I’ve made a start on my 2, so far so good! I’ve put all except 2 values of resistor down, as I didn’t have them, and started on the caps. More stuff arriving tomorrow hopefully, from Mouser, I got the rest of the caps and some of the silicon from them, I’ve only ordered 1 FPGA so far, and it won’t even be posted until after the 14th, all the Chinese eBay sellers seem to be on holiday until then! I still need to order a few bits, mainly switches, the toggles are quite pricey! I might go for alternatives from RS, since I’ll be getting the 16 position hex switches from there.

Regards
Lloyd

Re: Hedghog standards converter
 

Hi Lloyd,

If you wanted to keep it channel 1 until your hex switch arrives, just bridge the outer pad to the nearest of the four.

Re: Hedghog standards converter
 

I'm hoping to finish my Hedghog tomorrow:). I notice the rotary hex switch shows 0 to 9 and then A to F. Does channel 1 start at 1 on the switch and then A is for channel 10 etc?

Thanks
David

Re: Hedghog standards converter
 

Somewhere, in the last couple of days, on one of the various HH threads on one of the three Forums, I've seen the part number for the new, slim line case. Also for the vertical preset for the audio level adjustment.
I don't seem to be able to find them again! Could someone point me in the right direction?

Many thanks
Nick

Re: Hedghog standards converter
 

HI David,
That is correct.


Nick,

Farnell
108249 for 5k
108252 for 50k

TBH the gain control really only needs the initial setting then its fine.

1520397 slim case

Re: Hedghog standards converter
 

Hi Lloyd
The switches are one of the more expensive components. I know a constructor that used different phono sockets but he said he wouldn't do it again as it was more trouble than it was worth. It may be same with the switches.

I just took delivery on Friday of one of these lots. They are the 2 position type. I couldn't find any 3 position types on the same site. I have tested one in a PCB and the foot print is correct. The quality is not as good as the ones listed in the parts list but are probably OK. The actuator is longer than the ones listed in the parts list.
Photo below shows from top to bottom

RS Stock No. 734-7132 a 3 position type. It has a longer actuator than the one from AliExpress.
The one from AliExpress.
A MULTICOMP 1MS3T2B4M7RE which is in the parts list.

Frank

Re: Hedghog standards converter
 

Thanks for the part number information, Stephen.

The RS stock number for the 3 position toggle switch is 734-7132 £2.65 each
The RS Stock number for the 2 position toggle switch is 734-7107 £1.58 each

I have decided to stick with the original, larger case for my unit. It will give me greater flexibility if I want to do any modifications in the future. I have also decided to use chassis mount phono sockets & power socket. I think this will be more robust for the usage the unit will get. They are also simpler to source.

I have now compiled an order for all the parts in the most economical way. The only things coming from RS are the toggle switches & the hex switch. Everything else is from Farnell baring the two modulator IC's & the FPGA.

It took a while to sort out the 14 pin headers. By far the cheapest option was to buy 2x 50 way ones from Farnell for £1.10 each. I can cut these down to 14 pin ones.

Is there a recommended supplier for the FPGA dev board & 'blaster', or does one just have to take pot luck on Ebay?

Many thanks
Nick

Re: Hedghog standards converter
 

The 3 position multicomp switches are only £1.16 each at CPC;)

I also saved some money by buying only white phono sockets from ebay (£3.59 for 20) and added coloured circles to the front and back panel legends.

David

Re: Hedghog standards converter
 

Hi Nick
They will work fine but the actuator on the 734-7107 is shorter.

A 3 position toggle switch 734-7132 and
a 2 position toggle switch 734-7078 would have the same length actuator.

The 734-7107 is identical to the MULTICOMP 1MS1T2B4M7RE in the parts list but I don't believe there is a RS PRO version of the 3 position MULTICOMP 1MS3T2B4M7RE.

It is so long ago since I got my Blaster that I don't know who I got it from but I think it was a UK seller. I take pot luck buying the FPGA boards.

Frank

Re: Hedghog standards converter
 

Hi Dave
That's a great find. The 2 position switches are a good price too.

Frank

Re: Hedghog standards converter
 

Good spot David! That’s better than the ones I’d found on RS, they were made by TE Connectivity, part no’s 710-9612 for the 3 pos, and 710-9750 for the 2 pos. I’d actually forgotten about CPC! I’ll be sticking to the design as best I can, stands more chance of working then!

Nick, I just picked the cheapest of the FPGA boards that came with the USB blaster, mine came to £13.06. I need a second one, but I’ll get both Hedghog’s working with just one to begin with, then buy another without the blaster.

Regards
Lloyd