Please check my schematic

F

fizzit

Member
If you have the time could you give my Picaxe ROV schematic a look? I want to be sure everything is good before I breadboard it.
Notes:
-The PA18X up top is in the control box. Everything in the lower part is onboard the ROV.
-+2 is 5v from the 7805, + is 12v straight from the battery.
-JS = Joystick w/ two 10K pots (only one pot is used on JS2)
-The voltage divider on the 28X1 is to check battery voltage.
-The LEDs and buzzers on the 18X are for general indicating.
-Yeah, my component shapes are wrong. Sorry about that.

Thanks in advance, and be sure to post with any questions.

http://h1.ripway.com/bananafred/colin2.gif

EDIT: I have updated the schematic with my new enlightendness on MOSFETs etc. and created a breadboard with PEBBLE (which by the way is amazing).

So if you could have a look at my breadboard and do the same as before... :)
I left out the relays and motors because there is no good way to put them on the breadboard. Just assume that they are hooked up with the drain of the MOSFET on one side and +12v on the other side of the coil.

IC||443|270|1||U?|||PICAXE28|IC||PICAXE28_1
Wire||207|270|2|||#FF0000|3||||
Wire||207|105|2|||#CC6633|2||||
Resistor|4300|373|372|1|Resistor|R?||3||IC||
Wire||210|404|1|||#DFFF00|6||||
Note||1224|97|1||||||12V+||NOTEPAD_1
Note||1219|63|1||||||0V||NOTEPAD_1
Resistor|2200|471|409|2|Resistor|R?||3||IC||
Transistor|BC559|344|195|2|Transistor|Q?|||2|IC|SDG|transistor_22
Wire||342|105|2|||#CC6633|2||||
Resistor|82|400|236|1|Resistor|R?||1||IC||
Wire||480|184|1|||#DFFF00|13||||
Resistor|1000|831|208|1|Resistor|R?||2||IC||
Transistor|BC559|856|140|2|Transistor|Q?|||2|IC|SDG|transistor_22
Wire||855|105|2|||#CC6633|2||||
Terminal||924|238|1||TS?||3|4|Terminals||terminal_431
Wire||963|105|2|||#CC6633|2||||
Wire||990|270|2|||#FF0000|9||||
Wire||561|239|1|||#DFFF00|14||||
Wire||314|104|21||12|#FDFF00|11|14|||
Wire||479|240|13||11|#FDFF00|13|11|||
Wire||560|240|11||11|#FF9900|15|11|||
Wire||935|104|21||11|#FF0000|3|11|||
Wire||989|77|21||11|#FF0000|3|11|||
Wire||844|77|22||11|#FF0000|4|11|||
Wire||587|231|12||11|#3253FF|17|11|||
Terminal||1005|183|1||TS?||3|4|Terminals||terminal_431
Wire||1070|77|21||11|#FF0000|3|11|||
Wire||1018|269|23||11|#CC6633|10|11|||
Wire||342|77|21||11|#FF0000|3|11|||
Resistor|82|750|372|1|Resistor|R?||3||IC||
Resistor|82|777|456|1|Resistor|R?||1||IC||
Wire||829|432|11||11|#FF0000|7|11|||
Transistor|BC559|883|333|2|Transistor|Q?|||2|IC|SDG|transistor_22
Wire||881|407|21||11|#FDFF00|4|11|||
Wire||856|396|12||11|#FF0000|3|11|||
Transistor|BC559|964|333|2|Transistor|Q?|||2|IC|SDG|transistor_22
Wire||962|407|21||11|#FDFF00|4|11|||
Wire||641|203|12||11|#3253FF|19|11|||
Wire||614|188|13||11|#00A060|23|11|||
Transistor|BC559|1101|250|2|Transistor|Q?|||2|IC|SDG|transistor_22
Transistor|BC559|1182|250|2|Transistor|Q?|||2|IC|SDG|transistor_22
Wire||1099|77|21||11|#FF0000|3|11|||
Wire||1180|77|21||11|#FF0000|3|11|||
IC||1362|270|1||U?|||PICAXE08|IC||PICAXE08_1
Wire||656|214|22||11|#FF0000|12|11|||
Wire||683|214|22||11|#000000|11|11|||
Resistor|33000|581|410|2|Resistor|R?||3||IC||
Wire||639|462|21||11|#CC6633|2|11|||
Wire||506|176|12||11|#A233C3|31|11|||
Wire||1342|269|21||11|#FF0000|3|11|||
Wire||1344|451|12||11|#FF9900|4|11|||
Wire||1317|405|11||11|#FDFF00|4|11|||
Resistor|82|1265|374|1|Resistor|R?||1||IC||
Transistor|BC559|1209|333|2|Transistor|Q?|||2|IC|SDG|transistor_22
Wire||1207|462|21||11|#FF0000|2|11|||
Wire||1369|462|21||11|#FF0000|3|11|||
Wire||1369|77|21||11|#FF0000|3|11|||
Resistor|82|1454|237|1|Resistor|R?||2||IC||
Transistor|BC559|1479|195|2|Transistor|Q?|||2|IC|SDG|transistor_22
Wire||1477|77|21||11|#FF0000|3|11|||
Transistor|BC559|209|388|2|Transistor|Q?|||2|IC|+I G +O|transistor_22
Wire||207|77|21||11|#FF0000|11|11|||
Wire||234|77|21||11|#FF0000|11|11|||
Wire||261|462|21||11|#FF0000|3|11|||
Wire||927|242|22||11|#FF0000|11|11|||
Resistor|4700|447|465|2|Resistor|R?||2||IC||
Resistor|33000|1394|465|2|Resistor|R?||1||IC||
Wire||324|405|11||31|#FDFF00|2|31|||
BREADBOARDSTYLE=BB36
Click to expand...
 
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L

lanternfish

Senior Member
From what I have read in the manual and from serching this forum, you may run into trouble with using the PWM and servos at the same time. Of course, I am willing to be corrected on that! It may be an idea to move either the motors or the servos to the control of a single picaxe.

Have you considered using an L293D or similar instead of relays?

Cheers
 
L

lanternfish

Senior Member
Just checked your previous thread on PICAXE ROV. Now assuming that it is for this project. So please ignore my comment re L293D.

Cheers
 
D

Dippy

Moderator
Well, a new ruler would help :)

Are those funny things FETs / MOSFETs ?

I only had a quick glance as I'm not being paid, but why bother with FETs/MOSFETs for the LEDs ?
High brightness LEDs (cheapy Kingbright 12p from Farnell) + 1K res are bright enough to leave spots in your eyes. They are 'king bright.

And ANY circuit with motors and buzzy things really should have some decoupling caps next to each PIC power pins.

Also, take care with powering Piezos directly.
Is that a Piezo 'loudspeaker' or one othose 'Peepers' with the built-in driver?
Some of the 'Peepers' I've used can put loads of noise onto their supply wires and upset PIC.
In fact I've used 'Peepers' which, even though used just a few mA, reset the PIC due to noise.

If its a 'loudspeaker' type then decouple as suggested in the MANUAL 3 , search on 'SOUNDER' - and it is sometimes useful to put a small cap in parallel with piezo to reduce high frequency noise. You may like to add a few series ohms if the piezo has a very low impedance.
 
hippy

hippy

Ex-Staff (retired)
A few comments ...

I note you have your relay coils low-side to the MOSFET drivers - I don't know if that works but it's more common to put relays high-side. I don't know which is more advantageous or disadvantageous when the coil is switched off and the back-EMF is dumped into +V or 0V.

Top left PICAXE-18X, O4-O7, presumably those diodes are LED's, and will need current limiting R's unless pulsed in software.

Top left PICAXE-18X needs reset connecting.

Bottom left PICAXE-28X1 needs reset connecting.

Bottom right PICAXE-08M is using SIN, presumably Serial In, but 08M does not support SERRXD.

The two left PICAXE's also use SIN. Comment says "Download circuit omitted for convenience" - Not sure if that means, "Download circuit not used", or "not shown", but if the later it's not clear how it is to be used with what you have
 
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F

fizzit

Member
Ah. The download circuit. I was just going to put the 10/22k resistors on each chip, and for programming move them to a seperate board. Will that work? I put the diodes on the relays to absorb back-EMF. Maybe I should move all inter-chip communications to seperate I/O ports instead of the serial in and out ones.

@Dippy: The beacon LEDs need to be really bright. I'm hoping that 16 will be enough. The main light is about two watts + it's on 12v. So MOSFETs are needed.

hippy said:
A few comments ...

I note you have your relay coils low-side to the MOSFET drivers - I don't know if that works but it's more common to put relays high-side. I don't know which is more advantageous or disadvantageous when the coil is switched off and the back-EMF is dumped into +V or 0V.

Top left PICAXE-18X, O4-O7, presumably those diodes are LED's, and will need current limiting R's unless pulsed in software.

Top left PICAXE-18X needs reset connecting.

Bottom left PICAXE-28X1 needs reset connecting.

Bottom right PICAXE-08M is using SIN, presumably Serial In, but 08M does not support SERRXD.

The two left PICAXE's also use SIN. Comment says "Download circuit omitted for convenience" - Not sure if that means, "Download circuit not used", or "not shown", but if the later it's not clear how it is to be used with what you have
Click to expand...
 
B

BeanieBots

Moderator
Will the FETs turn on?
Impossible to say unless you state if they are 'P' or 'N' channel devices.
You have wired for 'P' channel but low side 'N' channel is far more common as indicated by Hippy. Please clarify which you are using.

No LED resistors:eek:
LEDs are CURRENT devices. NOT voltage driven.
They will die (and probably your FETs too) within a fraction of a second:eek:
 
D

Dippy

Moderator
Ah, so squiggle = P-chan MOSFET with 82R to Gate? (not base). Why 82R? (I guess you have lots in your drawer? ;) )

+ = 12V
+2 = 5V

So, you expect your P-chan MOSFETs to switch ON with Vgs = -12V , OK.
And switch right OFF when Vgs = -7V
Is that right? If so, Oh dear.


Go, with the suggestions above and use low-sided switching with logic-level N-chans, if you insist on using MOSFETs.

'Beacon' LEDs.
So, in your sketch, that single LED symbol refers to up to 16 LEDs?
How are they connected? In series? With a 12V supply?
And as mentioned , no resistors?

I think we're spending more time decyphering than you spent drawing it :)

A rethink and redesign would my Plan A.

PS. Norton comes up with a warning for ripway.com....
 
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F

fizzit

Member
Yeah. The parallel lines with one connection on one side and two on the other are FETs. Uhhh... I expect the MOSFETs to go on with 5v to base and off with 0v, no questions asked :p . I thought they were like relays w/ only one coil connection. The MOSFETs I chose are logic-level and well-suited. I will post a link soon. There are 3 series of 5 red leds running in parallel, though, on the beacon light.
 
B

BeanieBots

Moderator
fizzit said:
I expect the MOSFETs to go on with 5v to base and off with 0v, no questions asked :p
Click to expand...
Oh dear:rolleyes:
5v with respect to what exactly?

Keeping with your relay analogy, you can stick 5v on one end of the coil but whether or not it comes on (or even simply vapourises) depends on what's on the other end. Same with a 'gate' or 'base' of a transistor.

As already mentioned by Dippy, FETs don't have a "base", they have a "gate".

"There are 3 series of 5 red leds running in parallel"
That's still not 100% clear. How many in series?
Are they ALL red?
 
F

fizzit

Member
The LEDs are all red, of the same type. It is like this:
/ >| >| >| >| >| \
+12v -- >| >| >| >| >| - 0v
\ >| >| >| >| >| /

All in all, 15 LEDs. Current measured is 90ma.

Hmm, I should have looked into it more. A experienced ESC builder showed me the MOSFET I was planning on using. I will edit this post with the link to the exact chip later to clear lots of things up.

What exactly would keep it from working the way I have it, with a logic level high-power MOSFET?

EDIT!
MOSFET Link:
http://www.mouser.com/Search/ProductDetail.aspx?qs=sGAEpiMZZMveMCOqFR6qCOveJ5Fcf9UcP9k8RlWWZsM=
 
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D

Dippy

Moderator
You are expecting an N channel MOSFET to act as a lovely high switch by applying 5V to the Gate (again, NOT base) ??

"A experienced ESC builder showed me the MOSFET I was planning on using."
- I suggest he teaches you on how to connect it too.

The spec of a MOSFET e.g. the one you linked will usually give figures for Rds versus Vgs.
Note: that means the GATE (not Base) voltage With Respect To the SOURCE.
i.e. the voltage between the GATE and the SOURCE legs.

A MOSFET is N-O-T simply a device that you chuck in 5V and it acts like a relay. Any experienced ESC builder should be able to tell you that.

Thos MOSFETs will be fine (maybe overkill) as LOW sided switches for your relays and LEDs. Quite easy to change drawing.
When you have the MOSFET as a LOW sided switch then the Source is grounded, so when you trigger the GATE with PICAXE then the GATE is getting ~5V with respect to Ground = With respect to SOURCE i.e. Vgs = ~ 5V .

I honestly think you should just step back from this and spend an hour on basic MOSFET circuit designs. What you have currently is wrong (unless your sketch is wrong).
 
B

BeanieBots

Moderator
Agree fully with Dippy but in particular this bit:-

"A experienced ESC builder showed me the MOSFET I was planning on using."
- I suggest he teaches you on how to connect it too.

If you know somebody with even the slightest idea about FETs, talk with them. They will be able to explain face to face far more and much better than we can here. Even how to draw one and the difference between 'P' type and 'N' type would be a good start.
 
W

westaust55

Moderator
Fizzit,

Not sure if you have done a hand edit to your PEBBLE datafile.

You have two terminals in the circuit at different lines:
Code: 
:
Terminal||924|238|1||TS?||3|4|Terminals||terminal[COLOR="Red"]_ 4[/COLOR]31
:
:
Terminal||1005|183|1||TS?||3|4|Terminals||termina[COLOR="Red"]l _[/COLOR]431
:
In both a space has been introduced.
First case after the underscore
Second case before the underscore

Your datafile will not load into PEBBLE until those two lines are corrected.

I cannot replicate this in PEBBLE V2.2. The output I see from PEBBLE never shows a space. Please check you Load/SAVE source and advise
 
D

Dippy

Moderator
ALWAYS, put update/changes/additions in chronological order.
People get hacked off having to go back and forth checking updates.
And, as said recently, it can make subsequent comments look meaningless.
Leave your errors and it leaves the thread looking like a sensible progression.
Don't worry about emabarrassment.

I've seen 10 page threads where people have updated (e.g) post #35, and then expect people to click back and forth finding the darned thing. At that point I always click off.

Your post 1 implies you've updated your sketch and put a breadboard image in it too.
I couldn't see any signifiant changes if you have. Still the same erroneous use of MOSFETs as advised by the experienced ESC designer.
Maybe I got the wrong link.

Please supply a neat new sketch defining components properly on a plain sheet of paper and use a ruler. Or a freebie CAD.

And best you don't let this thread meander off into a pebble tutorial.

Most of us Old Hacks find it much easier to follow a proper/neat(!!!) schematic than an image of a beadboard.
No offence intended re B/board piccies, but looking at a breadboard means that we may have to spend time checking component pinouts against Data Sheets. At that point most of us will lose interest.

If you want help you have to provide all the information in a manner that is easily digestible.
Good luck :)
 
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