uPD2824 PLL expander concept / first prototype

A forum for the discussion of matters of a technical nature. All such activities are undertaken at the readers discretion and own risk. If you don't know what you are doing, don't blame us if it all goes wrong!
lbcomms
Radio Addict
Radio Addict
Posts: 505
Joined: 04 Oct 2015, 08:10
Location: Sydney, Australia

Re: uPD2824 PLL expander concept / first prototype

Post by lbcomms »

Except for the 8574 chips I have plenty of, I'll be ordering SMD versions of all the other parts tomorrow (Monday) morning, then it's wait for the slow boat/plane from China and HK. When all the parts are here I'll then do the PCB in spare time, this will depend on how much "real" work we have at the time. Once that's done and some boards have been made things should move along at a good pace.

I''ve got 3 more radios waiting here for them, but we've told the owners it's a strictly "spare time" job that will happen when it happens. Fortunately they are all regulars who understand these things and shouldn't harass us...
Mattylad
Top Poster
Top Poster
Posts: 1536
Joined: 03 May 2014, 20:09
Call Sign: RDX64
Location: Lancashire

Re: uPD2824 PLL expander concept / first prototype

Post by Mattylad »

Admiral wrote:I suspect the 'CB' reference may have been 'circuit board'.
It was a typo - I meant to type PCB. :oops:
User avatar
darkone
Radio Addict
Radio Addict
Posts: 544
Joined: 21 Feb 2010, 03:12

Re: uPD2824 PLL expander concept / first prototype

Post by darkone »

If you're going to the trouble of SMD and having a board made up why not design out the need to cut PCB traces?
Butchering the board is one of my pet hates; fine for a prototype but not for production :(
"Far from idleness being the root of all evil, it is rather the only true good."
Soren Kierkegaard - Danish philosopher (1813 - 1855)
User avatar
cjay
Top Poster
Top Poster
Posts: 1775
Joined: 06 Jun 2013, 21:21
Call Sign: cjay
Location: Manchester
Contact:

Re: uPD2824 PLL expander concept / first prototype

Post by cjay »

darkone wrote:If you're going to the trouble of SMD and having a board made up why not design out the need to cut PCB traces?
Butchering the board is one of my pet hates; fine for a prototype but not for production :(
One of mine too, I have a couple of Jumbos which hav had PLL inputs butchered, absolutely mind boggling as the channel switch is connected with six wires that desolder really nicely.
Mattylad
Top Poster
Top Poster
Posts: 1536
Joined: 03 May 2014, 20:09
Call Sign: RDX64
Location: Lancashire

Re: uPD2824 PLL expander concept / first prototype

Post by Mattylad »

I suspect that the problem will be making it so that many different radios can be modded with it - they will all have a slightly different layout (sods law).
lbcomms
Radio Addict
Radio Addict
Posts: 505
Joined: 04 Oct 2015, 08:10
Location: Sydney, Australia

Re: uPD2824 PLL expander concept / first prototype

Post by lbcomms »

darkone wrote:why not design out the need to cut PCB traces?
There are three places where the prototypes needed trace cuts.

1) The display driver section of the addon board. There are two types of 7 segment displays, common cathode and common anode. With the common anode type, an 8V, 13.8V, or variable voltage (from a dimming circuit) is fed to the common pins of the display, and the segment cathode lines are grounded (through a current limiting resistor) to light up the segment. With the common cathode type, the common pins are grounded, and the segment anode lines are connected to a positive voltage (again through a current limiting resistor) to light up the segment.

The display driver IC can only output 0V or 5V, so it can't be used with the common anode type if the dimmer function is to be retained, the segment would not be able to be turned off. To overcome this, a pair of ULN2003 ICs are used, these are open collector and when turned off will become open circuit and turn the LED off, no matter what the voltage is at the anode.

Alternately, the dimmer could be disabled and the anodes rewired to 5V, but that's a lot more work (more trace cuts too) than the $1 pair of ULN2003 ICs.

The ULN2003s are not required for common cathode displays though. Originally I was going to have traces that could be cut for making the common anode variant, but in the end made a custom SO16 footprint with 7 solder links fitted without the ICs for common cathode and no links but the ICs fitted for common anode, no need to cut traces there anymore.

2) The board that the display LED is mounted into. Japanese sets have all 14 segments wired separately, those are easy. Others, such as the Taiwan / Philippines President, Cobra, and Uniden 40 channel radios, wire the top and bottom (a and d) segments of the tens digit together to save themselves a one cent resistor. Because of this cheapskatedness, a trace cut is needed so it can be wired to display a "7" on the tens digit.

3a - expandable PLLs) The PLL IC program pins wiring to the channel switch need to be isolated from each other, as the two now provide an independent function. Only way around a trace cut here would be to remove the channel switch and wire it to the addon board somehow. This would be difficult on some radios and impossible on others, such as the small SSB mobiles that solder the channel switch directly to the main board. Even then, the hard wired programming pins would still need trace cuts to isolate them.

3b - non-expandable PLLs) The input divider section of the existing PLL needs to be isolated from the rest of the PLL circuit, so the new board can trick it into going to the new channels. There is a possibility here for the coupling parts to be just removed to save trace cuts, need to look at a few other PLLs (such as the LC7131) before deciding that it's possible for all PLL types, but looking good at this stage.

Any suggestions on overcoming #2 and #3a would be certainly looked at :)
User avatar
cjay
Top Poster
Top Poster
Posts: 1775
Joined: 06 Jun 2013, 21:21
Call Sign: cjay
Location: Manchester
Contact:

Re: uPD2824 PLL expander concept / first prototype

Post by cjay »

2, there doesn't seem to be an answer other than a new LED board or trace cuts.

3a I have considered making an interposer board, simple little board that takes the PLL in a socket perhaps and extends the necessary pins down to the original board but breaks out the programming pins and others that need to be isolated to a set of pads for the new control signals. Might happen now I can get boards made for dirt cheap, it'd be a simple matter to have a few standard size boards made up and only add 'riser' pins to the pads that need them.

3a would also work for 3b but it'd need to be tested to ensure it doesn't introduce any unwanted effects
User avatar
darkone
Radio Addict
Radio Addict
Posts: 544
Joined: 21 Feb 2010, 03:12

Re: uPD2824 PLL expander concept / first prototype

Post by darkone »

For PLL either a board as Cjay suggests or lift one edge of the PLL IC.
Board for each IC type with a common IDC header or some such to connect to you driver board perhaps.

I'm not au fait with all the LED configurations but don't all of them have limiting resistors either individual or dips? If you housed the resistors on your board you could use the existing resistor solder points?
"Far from idleness being the root of all evil, it is rather the only true good."
Soren Kierkegaard - Danish philosopher (1813 - 1855)
TM86
Regular
Regular
Posts: 40
Joined: 13 Jul 2015, 02:04
Call Sign: 2TM86

Re: uPD2824 PLL expander concept / first prototype

Post by TM86 »

Another approach was needed.
Indeed, another approach was. Thanks for the tip on interrupts.

I've now got a breadboarded circuit acting the way I think it should. Once I have a few hours without my 18 month old house guest ripping things apart for laughs, I'll hook it up to the Cobra 2000 and see how it goes.

The breadboarded circuit, not the child. Children are not good radio mods, don't ask how I know this.
lbcomms
Radio Addict
Radio Addict
Posts: 505
Joined: 04 Oct 2015, 08:10
Location: Sydney, Australia

Re: uPD2824 PLL expander concept / first prototype

Post by lbcomms »

cjay wrote:3a I have considered making an interposer board, simple little board that takes the PLL in a socket perhaps and extends the necessary pins
We did this a while back for a guy with an immaculate President Adams that the owner specified trace cuts (except where there was absolutely no other way) were to be avoided, no matter what the cost. We got an intermediate board made up just for that radio, the owner was happy to pay for our design time and the fab costs, for what he spent on it he could have bought a decent secondhand commercial or ham HF radio that covered 1.8-30 megs with 100W output. His radio, his money, his choice - but most folks are working to a budget. I could get a some made for each chassis, but that would mean maybe 10 different designs that would take years to sell them all.

I'll leave that one for the really keen ones - the universal board we are making has a 10 way IDC header for the PLL wiring, they could always make up a riser board with the same connector type on it and use a 10 way IDC-IDC cable to join the two.
3a would also work for 3b but it'd need to be tested to ensure it doesn't introduce any unwanted effects
The first one we made did have unwanted effects that made it unusable on SSB. That one used a simple single sided board, RF issues galore. A double sided board with the unused areas of the board filled with a groundplane both sides (joined with vias every 1cm) solved that one. It was a universal design that needed two trace cuts on the radio board, the next one will have a simple change that will save the need for this, on the uPD28xx and LC71xx PLL radios at least. This main reason is for installation speed and simplicity though, not to save the radios board from my scalpel...
lbcomms
Radio Addict
Radio Addict
Posts: 505
Joined: 04 Oct 2015, 08:10
Location: Sydney, Australia

Re: uPD2824 PLL expander concept / first prototype

Post by lbcomms »

darkone wrote:I'm not au fait with all the LED configurations but don't all of them have limiting resistors either individual or dips?
Yes, the Japanese radios use a pair of 7 way DIPs, the others use 13 individual resistors (one at half the value is used for the top and bottom of the tens digit, the others are individuals).
If you housed the resistors on your board you could use the existing resistor solder points?
Yes for most of them, just the joined tens segments "a" and "d" need to be separated and fitted with individual resistors.

However, fitting the wires to 13/14 holes is messier and more time consuming than just soldering to 2 rows of pins on the display. Most folks want cheap, this means designing to make the installation as quick as possible...
lbcomms
Radio Addict
Radio Addict
Posts: 505
Joined: 04 Oct 2015, 08:10
Location: Sydney, Australia

Re: uPD2824 PLL expander concept / first prototype

Post by lbcomms »

TM86 wrote:I'll hook it up to the Cobra 2000 and see how it goes
That should be easy, you only need to drive the PLL (no display drive needed), you can just look where you are on the counter :)

Are you using something like a ULN2003 or an MC1413 to separate the 3.3V or 5V logic voltage from the 8V on the PLL programming pins?
Children are not good radio mods
They are, given the chance. We don't see much "kiddie" damage as most of our work is with business and industrial gear, but there was a place next door to us before we moved 10 years back that did car audio, TV/VCR, and similar domestic electronics. He kept a list on his wall called "kiddy mods" of all the things he had found pushed into disc and tape slots - toys, stones, coins, sweet wrappers, chocolate, tin foil, broken toy parts, moldy chewed up savory food, the list was two pages long...
User avatar
cjay
Top Poster
Top Poster
Posts: 1775
Joined: 06 Jun 2013, 21:21
Call Sign: cjay
Location: Manchester
Contact:

Re: uPD2824 PLL expander concept / first prototype

Post by cjay »

lbcomms wrote: They are, given the chance. We don't see much "kiddie" damage as most of our work is with business and industrial gear, but there was a place next door to us before we moved 10 years back that did car audio, TV/VCR, and similar domestic electronics. He kept a list on his wall called "kiddy mods" of all the things he had found pushed into disc and tape slots - toys, stones, coins, sweet wrappers, chocolate, tin foil, broken toy parts, moldy chewed up savory food, the list was two pages long...
Ha, I used to do that for a living, I had a very similar list and so did quite a few other techs, Top-Loader videos could be the worst, more than a few drinks down the pub and then home for a video, leaning over an open top video recorder and you can guess the rest.
TM86
Regular
Regular
Posts: 40
Joined: 13 Jul 2015, 02:04
Call Sign: 2TM86

Re: uPD2824 PLL expander concept / first prototype

Post by TM86 »

Are you using something like a ULN2003 or an MC1413 to separate the 3.3V or 5V logic voltage from the 8V on the PLL programming pins?
For the breadboard circuit I'm driving the PLL with 5v straight out of the MCP23017 to the PLL pins. It's not a long-term solution but then I wasn't having trouble with the output side of things.

Once I move on to a soldered board, I'll steal your idea and use a ULN2003 or equivalent.
Children are not good radio mods
They are, given the chance.
I'm not saying it can't be done. I'm just saying it's hard to solder them into the circuit.
User avatar
zippy
Super Member
Super Member
Posts: 209
Joined: 02 Nov 2015, 10:43
Call Sign: 26TM537
Location: Hatfield Herts

Re: uPD2824 PLL expander concept / first prototype

Post by zippy »

this is very clever stuff but the Chinese have already flooded the market with 12m-10m continuous multimode radios that can be bought for £100 brand new.
I don't get the logic of some of your customers when thet want this original, don't cut that, leave this alone, and yet theres a dirty great board in there prescious radio with a computer on it. 'oh yeah man I may want to take it back to original one day like', well don't bugger about with it then if originality is your thing, buy a classic and put it on your shelf and dust it every day and admire its beauty, then buy a 2015 Chinese set to use.
your skills are without question lbcomms, your cb customers are questionable in my opinion.
Alinco DR135DX, Baofeng UV-5R, TYT MD380 (UHF), Realistic Pro-2035, JRC NRD-545 DSP, whitestick and ½ wave silver pole on the chimney and various lengths of wire draped around the garden.
Post Reply