Nick Mulder

pdf is 3.3MB hmmmm here's the PSU pages though... Too small ?? :P

Hello, My stereo amp (NAD 317) when I turned it on started making a ratcheting up buzzer noise which would last about half a second then 'start up' (some relay would click on and all was well)... This lasted a few days until this weekend when I was going to have a look at it but today it no longer switches on or anything, power = nothing ... Take a look at the photo - I'm getting AC past the fuses at 'C' (checked the fuses to be sure) - and 15v DC at both left and right amplifiers +VL ('B' is left) - I dont see any negative DC though on the -VL wires (is there meant to be -ve ?). I figure the noise had a typical relay buzzer sound to it and suspect it could the relay marked 'A' (48V 250VAC) - there are relays on the audio inputs, but I just don't think its them, of course I'm open to any suggestions as to what is going on... Has some cap failed in the AC to DC power doohickey ? ~What to check, and how to check it ? any help appreciated, N

The square wave Its the output of an LDR, which is conditioned into the red line signal which is then scaled appropriately to be sent to various analog synthesizers ... There will be at least 10 of these sensor set ups. The idea was to keep it all analog, but maybe a bunch of sample and hold circuits could be interesting, once the sample rate is clocked with the square wave frequency and then phased correctly with the highs then I'd be getting pretty much exactly what I'm asking for huh ! - is there a way of achieving that with cheaper and/or analog components ?

this might be interesting reading: http://www.electronics-lab.com/forum/index.php?topic=9124.msg52348#msg52348

I remember asking the same thing here years ago ... Exactly the same issue - you have an output range from A to B and you want to scale it linearly so that A is now A1 and B is B1 A1 and B1 are within reason arbitrarily related to A and B - easy to do in code (with the possible resultant resolution drop), but harder to do with analog electronics Scaling (multiplying/dividing) is easy Adding voltage is easy Some sort of simultaneous equation involved with a circuit - but if I recall subtracting voltage is the hard part Say you wanted the signal ranging from A to B to equate to A-x to B-x - how is that done ? probably simple, I just forget Was about to search for the thread again myself, but they seem to have been purged - may as well tag onto this thread huh ;)

Hello, Question simplified: Say I had a 48Hz square wave whose high V value was modulated over time (see the black line in the first attached graphic) and I wanted to extract and output the curve of the modulation as a voltage (the red line)... How would I go about this ? Some thoughts that may or may not be helpful/relevant: The signal I am after is a low frequency signal compared to the one 'carrying it' (not to be confused with PWM!) - I thought that by simply adding a steep low pass filter I might be able to get way with it. But there is the worst case scenario to think about which is represented in the second graphic, imagine the 'high signal' were to fluctuate between max and min values as it does in the green box area, without a very (?) steep LPF how can I save that output from the filter ? (a 24Hz signal) I was thinking of a combination of a LPF to get rid of all the higher frequency harmonics of the square wave but combined with a high-Q band stop filter set at 48Hz ? I don't know much about the electronics here - just talking in terms I've learned from synthesizers /// Again, not getting confused with PWM but thinking about it in terms of duty cycle it would be an odd situation where a %50 cycle would give a constant voltage if the high value if the original square wave yet a %25 duty cycle (the worst case scenario) would give a 1/2 freq (sine?) wave whose range was equal to the high voltage of the original square wave. Yep, its what I want, but is this odd or what ? (addendum: I am aware that the red line appears to be 'aware' of the future signal path of the square wave in the graphics, I mean this to be real time so its output would of course lag behind the square wave signal, its just clearer in the graphic to display it this way)

working now :) - So there is also a bit of work to do on the uP programming but I understand what is required (I'll need a 16bit I/O expander as well) - hmmm, so what are all those NOR gates doing like that ? I am yet to understand them ...

I'd like to check it out but clicking on the pic or the text link below it pops up a window saying: You are not allowed to access this section Is there a paid subscriber function here ? I hope I'm not being rude asking if you could post the schematic elsewhere ? :-X thanks for your help! Nick

Yep, thats definitely a start! What do you have in mind ? btw - the bottom limit off 100Hz is only because of the mechanical limits in the system thats its going to be finally impaled upon - it could go down to zero if need be, although the parts might not like that ! the odd frequencies I need i can sort the analog way using that voltage-freq chip I'll use for the ramping - hopefully a bit of nichrome wire will get things accurate enough with a adj Vreg and It'll stay that way with temperature etc... I'll have to see

I was thinking yes I could enter Hz values into a uP and have a nifty LCD and telephone pad interface and let it do the math for me - but I'm still stuck with the same problem all along ... ok at one end in terms of resolution but then it all gets out of whack a the other end of the spectrum... Its because of the range I need, a factor of 10,000 (5 BCD values) - I'm hoping for 10,000 but maybe 1,000 is what I am stuck with because of pin counts on whatever I use It was suggested I look at this chip also http://www.st.com/stonline/books/pdf/docs/2086.pdf - which is neat in some respects but I'm still unsure how to 'cascade' it for want of a better term: I can see how to get 800Hz from a 1kHz input by simply inputting 8 in BCD (1000) via a thumbwheel BCD switch - but how do I get say 1238Hz from 10kHz ? maybe thinking like this: 0.1x10000 + 0.2x1000 + 0.3x100 + 0.8x10 = 1238 I can get the 0.1x,0.2x,0.3x etc.. factors individually from say four 4527 chips but how do I achieve the '+' ? '+' isn't quite the right way to think about it as we are dealing with frequency as opposed to discrete period of time - I hope I'm making sense and its a way forward ... On page 5 of the spec sheet though - it does some funky things with the duty cycle that will need to be smoothed out somehow! yikes, :P+ :D Nick

Just read your last reply - I'm understanding the 4059 a bit more now and should note that I meant the 4017 when i referred to the 4024 in my last post ... Like I said tho I'm still stuck with dividing periods rather than working directly with Hz - I want the value entered on the thumbwheel to be the frequency and not the frequency divisor. I'm getting an idea of how it works but this gear need to be used by other people who don't have the time to figure out the division, yes I know it only takes two secs... but the thing is I know that gear has been made that doesn't require it (just like that first linked to in the original thread) and that is the goal that I wish to achieve here ... So far I get the picture that there isn't an accurate way of deriving Hz directly - its always a division of a higher frequency with the remainders thrown into a +/- value postscript ? ...and if you need Hz on the user interface its always a convoluted method (I'm yet to understand) to translate this into the divisions ? thanks so far! hopefully Im not being a pain nick

Okidoki - I've found some BCD thumbwheels locally: http://www.jaycar.co.nz/productView.asp?ID=SR1250&CATID=&keywords=bcd+switch&SPECIAL=&form=KEYWORD&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID= So each digit is represented in a 4 bit nibble (the unused reserved for Hex I'm assuming) - I have a couple of the little style hex ones you use a screwdriver on here to play with already until I want to buy the more expensive thumbwheel dec versions ... So, I have a nibble representing each of my desired decimal factors for instance: 150.2Hz 0000 0000 0001 0101 0000 0010 (which is 001502, or 1,502 which would be divided by ten at the end) I'm not up to scratch with the 4059 but have used things like the 4024 and 4060 before (So I understand the divide by 10 section, with the 4024) So what exactly do I do with these 6 BCD values ? I could restrict my range from 100 Hz to 9999 Hz and then I'd only have four BCD values if that helps - but 100.0 to 9999.0 HZ would be preferred (5 BCD values, instead of my original 6) Doesn't the 4059 require the divided by number ? not the number that will result at the other end ? Say I want 300Hz and I've got 1MHz going in I'd need to enter into the 4059 'divide by 3333' - which will give me 300.03Hz Yet say if I wanted 9999Hz : 1,000,000 / 9999 = 100.0100010001... with the 5 BCD resolution I get the following: 1,000,000 / 0100.0 (hundred) = 10000 which aint 9999 Still - I find myself stuck working with dividing periods instead of entering frequencies directly ...confused - I probably got something wrong with your suggestion... any help appreciated, nick

Hi, I would like to build an device that provides a %50 cycle 0-5v square wave (easy!) - that has a range of frequencies that can be directly inputted from 100.0 Hz to 10,000.0 Hz (harder!) - I would like the 0.1 increments if possible ... I've played around with a microcontroller called the ooPIC but that always works in terms of setting the cycle period - because of this the frequency is always at the mercy of the resolution of the cycle period and I cannot achieve specification I outlined above... The device here: http://www.duallcamera.com/store/items/SpeedControls/MilliframeController.shtml is what I am attempting to emmulate... It has a decimal rotary wheel 'thingy' on the front where the user simply enters the Hz required and then away it goes... How is this done ? I was thinking that something like a Voltage to Frequency chip would be the go like the LM331 URL=http://cache.national.com/ds/LM/LM231.pdf - and maybe an array of adjustable vRegs that switches would add or remove resistance to achieve the voltage required (probably some nicrome wire involved) - there would be one Vreg and ten resistors per decimal point if you get what I mean ? all connected in series (or not, depending on the switch state) Bulky! I would/could also have the option of putting on a Adj Vreg that could sweep all the speeds required and some sort of feedback as to what speed it was set at via a microcontroller (like the ooPIC which I have here working) and an LCD - so the ooPIC would just be reading the freq as opposed to setting it (which I've had issues with in terms of resolution) - I'm still yet to figure out if it can read things with the res I need - I hope it can as I dont want to walk around with a scope! :P If I did this I would probably have a course adj Vreg and a fine adj Vreg so I'm not having to nudge the pot with ever so delicate fingers... Any suggestions appreciated ! I'm open to a totally different system if you have one in mind as I'm sure there many ways to do this ... ;) [shadow=red,left]Nick[/shadow]

The LDR cct is nice now, especially with the LPF on the input ... I have a problem with having too many projects on the go at once - I will move onto one before completing the last... The LDR cct has taken a back foot as it is not really required until the new year - the latest project is more mechanical in nature apart from the wireless modules I have purchased for it: http://www.maxstream.net/products/xbee/xbee-pro-oem-rf-module-zigbee.php These are the precious little static sensitive parts ... thanks for your info, always appreciated Nick

Hi, I have never had problems with zapping components in digital ccts and have used a fair amount of different components that came in the static sensitive device bags... The other day two components arrived in the aforementioned bags and they are worth $32US each. I thought it would be a good idea to get a antistatic wrist band in this case... I'm not working on PC cases, just my own breadboard cct's and microcontrollers Question: Do I have to connect to the actual household earth (both cct and band) ? or is it ok to only connect to the ground of my battery powered DC circuit ? What about the component just by itself ? if I connect the ground pin to the wrist band is it ok to touch the rest of the pins ? My intuition says plug myself and the cct ground into the wall (correctly!) I'm keen to get this stuff learned and out of the way ;) Thanks, Nick