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Mirror Camera project

PostPosted: Sun Apr 13, 2014 9:38 pm
by Harry Dalek
I started playing around with an idea today i found a not to old Brother laser printer on the nature strip last week didn't even bother to see if it worked still, i just wanted the polygon mirror and motor !
This has got me working on a camera idea l i always wanted to try a camera with mirrors i am casing it in an external aluminium dvd cd case have a Old video camera lens hooked up to it already i am still thinking if i should use vibrating mirror in resonance for the frame frequency since i have been playing around with this idea .
I like the polygon but i may have problems using the motor as its very different to the last one i used on the nbtv laser tv a year or 2 back .
Any case i am going to concentrate on line frequency motor control more than an thing as it was my down fall last time .

Re: Mirror Camera project

PostPosted: Wed Apr 16, 2014 10:30 pm
by Harry Dalek
Today i had a go at trying to get that motor to move ,i had no luck via is detached control board perhaps thats why it was dumped who knows, still the polygon mirror is mounted very stably much better than i could do.
So keeping it where it is and using another flat dvd player DC motor i will use pulley system to drive it as in the photos.
How i am planning the optical side i rather the lens image frame to the frame frequency mirror then the line mirror mainly due the the size of the mirrors which is logical full frame to a larger mirror width size and line frequency to line thinner mirror .
I am still thinking about placement for the frame mirror as i might use a mirror just to reflect the lens image to it first we will see optics gives me a headache :roll:
I am still leaning towards a frame frequency mirror driven by resonance to see if it really works ,i suppose its no real problem to see and if not replace it with a 4 sided mirror on a motor i know that works for sure .
The plan for line sync pulse to use a opto interrupter via the polygon as it rotates and see if i can sync the motor speed via that to my clock .

Re: Mirror Camera project

PostPosted: Fri Apr 18, 2014 9:08 pm
by Harry Dalek
Today i looked into tackling the optics side of things.
First up i had a problem of the old video camera lens output size ......what my mirrors need to see was a touch small,i found another small lens just the right size from another video camera and gives me a much larger size image to work with when used with this camera lens .

Next the part i am not great at the reflecting of the image to the X and Y Axis mirrors but using a laser i could see my first idea for the placement of both would of been wrong so a little rearranging of the mirrors i have now an idea where they should be thanks to my laser pen.

Again the framing frequency idea might change as i have a few options the 12.5 hz mirror its currently on a relay as it can handle a large glass mirror ,i have a 4 sided rotating mirror which is more than likely a better option all depends on what works what fits.

Re: Mirror Camera project

PostPosted: Mon Apr 21, 2014 10:02 pm
by Harry Dalek
I didn't have much time over easter ,i have so far light proofed the front of the case and added a opto switch for the line sync,i suppose it doesn't matter in my case where its located its not a 32 sided mirror.

Sorry messy block diagram but my first idea to work on the design.
I have made the clock using the 4060 ic nice to have a 400hz and 12 hz out of the same ic ,see if i can manage to get the motor control with the bistable circuit i used a while back .
I am trying to select circuits for a of minimum complexity,i think i can also fit all the electronics in that case .

Been looking at a lot of old newsletters as i am a big fan of Alan Shorts cameras wish he was on the forum ,last i read he was on hes 57th camera and i am pretty sure most of those were mirror types he tended to use a vibrating light sensor on a rod than using a second mirror well most of the time ,i think he was from Adelaide south Australia hope hes still with us constructing cameras ?

Re: Mirror Camera project

PostPosted: Sat Apr 26, 2014 7:28 pm
by Harry Dalek
Didn't have much time again last few days so i have been itching to get stuck into it again .

Took me a little while to work out the opto switch connections this was also a scrapped thing out of that laser printer.

After that it has been easy going to knock together what i have done so far and happy it all works fine ,the time i had to think about the circuits i ended up changing a few things very much so on the monostable pulse width control of the sync pulse and went with the 4528 and dropped the 555 this time .

I am going to try a simple 555 bistable a little different to the last one i used for motor control see how that gos always the old fingers crossed :wink:

The 4060 would of cause work better as a crystal oscillator don't have a spare crystal for it at the moment so this will do for now.

This is BTW only what i have done so far work in progress !

Re: Mirror Camera project

PostPosted: Sun Apr 27, 2014 5:03 pm
by Harry Dalek
It doesn't look like much but a rather productive day working on the camera ,i needed to get the speed control working so i tackled this today .
I had to change the clock to pin 2 and opto switch pulse to pin 4 on the bistable, i tacked on the club circuit to control the motor but had to change it a little to get it to work removing the first 100k resistor and changing the 4.7 k at the drain to a 18 ohm before the 10 k pot worked and using a irf 630 mosfet.
Also swapped from 5 volts to 12 volts for the motor.

Seems to work well ,i can get on to the sync and video mixing part next this week ,i think i am going to use the clubs video sync mixer circuit i might change it a little to get it to work on this project .

Re: Mirror Camera project

PostPosted: Mon Apr 28, 2014 6:17 pm
by AncientBrit
Keep up the good work Harry.

It's looking good,

Cheers,

Graham

Re: Mirror Camera project

PostPosted: Mon Apr 28, 2014 11:32 pm
by Harry Dalek
AncientBrit wrote:Keep up the good work Harry.

It's looking good,

Cheers,

Graham


Thanks Graham
I will try my best to get it going every thing seems to be going together well.
I am also taking in advice i have been given in the past and reading advice given to others so theres a mix of ideas in this one .
Really not to much more to do i have a head amp made up so i will give that a go,the video sync mixer and use the 12 hz out of the 4060 to second half of the monostable ic so i can adjust the pulse width and feed this to a trany which i will try on the relay vibrator for the frame .
I have a goal i would love it to do if i can make it work .
i would like it to be portable so a hand held camera so battery operated,the plan is to feed the signal to an iphone its app a sound recorder and record out doors in day light,it would be nice but need to see those first images before i can hope for any thing like the above.

Re: Mirror Camera project

PostPosted: Tue Apr 29, 2014 8:31 pm
by Harry Dalek
Just finished most of the video sync mixer i haven't tested it yet ,might just put an output plug in making testing easier.

I am just adding the sync to the bc109 will not be using the opto circuit as in the drawing.

Then I just have to do the last part hook the the frame frequency circuit up to the vibrating mirror and head amp see how it all gos ?

Re: Mirror Camera project

PostPosted: Thu May 01, 2014 11:36 am
by Harry Dalek
Ok i have got the video sync mixer going i had a problem not with the main circuit but the CA3140E ics i had 3 of them one didn't work at all dead the second partly worked and the 3rd was fine so i have improvised replaced the first ic with a old 741 and used the CA 3140 that works as the second ic and runs fine ,this will do till the next vist to the local electronics store. :mrgreen:

Now i am moving on the to 12 hz framing side of things and might look again at the 400 hz sync pulse width sync control seems a bit tight on the control side of things, its bothering me ...I will report back :wink:

Quick edit ...on the sync pulse worked it out slight change to the 4528 part of the schematic coming up ,just need to put in a power transistor for the 12 hz pulse and feed the relay .

Re: Mirror Camera project

PostPosted: Thu May 01, 2014 8:18 pm
by Harry Dalek
Worked a bit more on it today i have a lot done now so getting close for testing.

Heres the schematic so far! Happy with line motor control and pulse width control 400 and 12 hz ,i just finished the relay mirror frame control and have not tested it fully yet the mirror does vibrate better just using the 4060 pin 2 but i have not even had time to adjust the monostable pulse width control as i had to pack it up today and do other stuff.

So things could change on this front when i get back to it just you have an idea and need to test it see how it gos ,i forgot to put in which mosfet i am using its a 2sk2876 more than likely junked from a old tv.

When i am happy with my vibrating mirror control i will hook up the head amp.

Re: Mirror Camera project

PostPosted: Fri May 02, 2014 11:45 am
by Harry Dalek
Testing the mirror via the monostable ic ,i now have it working via it but not much control via pulse width but i might have the pulse width duration wrong so i am not sure yet if its a good control for this ,reason i put in a voltage adjustment for the relay and mosfet as i knew from my vibrating experiments this was a good control .
Looking at the mirror tilt the 32 lines are going to have to fit into the amount of tilt it does so focusing in on this area also i may need a mask slit if i use a solar cell as the polygon mirrors reflecting line would be to thick it may be easier to use a photo trany ,i suppose i will find out when i get up to all that .

I have to take back what i said about the pulse width control i hadn't adjusted the voltage correctly to the relay mosfet part of the circuit and now the pulse width control sure does control the relay vibration...

The 12 hz is by the way now out of pin 9 on of the monostable .

Re: Mirror Camera project

PostPosted: Sun May 04, 2014 9:33 pm
by Harry Dalek
Again not much time over the weekend but looking into shrinking the head amp due to space i think i can still use the one i made but i'd like to mount it in an area it fits .

I tried this design today but had a bit of trouble after transistor 2 it works fine output of transistor 2 but very poor after transistor 3 ,i tried changing resistor values and transistor still poor results at that transistor stage .

I am using Bc108 transistors perhaps its that reason and using a 9 volt battery not 8 volts ?

Any case i enjoy making the head amp stage i just use a crystal ear phone hear how well it works your hearing is a good test instrument for these things.

Re: Mirror Camera project

PostPosted: Mon May 05, 2014 12:39 am
by Steve Anderson
Hi Harry,

Just as an exercise I simulated the circuit above and really there wasn't that much change from 7, 8 or 9V. (See below) A slight increase in gain at 9V, a slight decrease at 7V - as you'd expect.

Frequency response shows a boost at 2kHz and over as expected, the LF bump can be ignored.

Red=8V, Green=7V & Blue=9V.

Instead of expensive BC109Cs use BC548Cs or BC549Cs, better (maginally) than the originals...drop-in replacements.

Gain and frequency response will be dependant on the characteristics of the solar cell to some extent...

Why R6 (original diagram) needs to be such a strange value is beyond me...there is even less change than the variation of supply volts between 2k2 or 2K7...even varying the temperature between 0, 27 and 70 Celcius made little difference. Also a Monte-Carlo run with 10% resistors was no issue...

erm...what I don't see in your photograph is any supply decoupling/bypass capacitors - unless you've hidden them on the underside (I often do)...this is a hi-gain stage and given the chance it will burst into oscillation...at many MHz, often beyond the ability of oscilloscopes to catch it...the Ft of BC10x transistors is over 100MHz...i.e. they (just) have gain at these frequencies...and that's all they need to become a headache...

To be honest I would suggest a simple lo-noise op-amp, a LM833 or a NE5532, simpler and stable.

Steve A.

Re: Mirror Camera project

PostPosted: Mon May 05, 2014 6:56 pm
by Harry Dalek
Steve Anderson wrote:Hi Harry,

Just as an exercise I simulated the circuit above and really there wasn't that much change from 7, 8 or 9V. (See below) A slight increase in gain at 9V, a slight decrease at 7V - as you'd expect.

Frequency response shows a boost at 2kHz and over as expected, the LF bump can be ignored.

Red=8V, Green=7V & Blue=9V.

Instead of expensive BC109Cs use BC548Cs or BC549Cs, better (maginally) than the originals...drop-in replacements.

Gain and frequency response will be dependant on the characteristics of the solar cell to some extent...



Thanks Steve for the reply and work there !

I used BC 108s i only had those and BC 107s handy some i scrapped ages ago ,i do have many BC 548s and 9s i just wanted to use up the old ones give them a second chance at working in a circuit ,oh yes on type of solar cells the large one i tried first as in my flying spot head amp it didn't work at all well i took it off and i could tell the first two stages of the circuit had been working fine connected the small solar cell and results were much better .

Why R6 (original diagram) needs to be such a strange value is beyond me...there is even less change than the variation of supply volts between 2k2 or 2K7...even varying the temperature between 0, 27 and 70 Celcius made little difference. Also a Monte-Carlo run with 10% resistors was no issue...


Whoops I missed that lower resistor value ! Still stage 1 and 2 work fine .. all the trouble is with stage 3 i don't think i have made a mistake but its more than likely since i missed that second resistor out right ! i will do more fault finding when i have time this week.


erm...what I don't see in your photograph is any supply decoupling/bypass capacitors - unless you've hidden them on the underside (I often do)...this is a hi-gain stage and given the chance it will burst into oscillation...at many MHz, often beyond the ability of oscilloscopes to catch it...the Ft of BC10x transistors is over 100MHz...i.e. they (just) have gain at these frequencies...and that's all they need to become a headache...


I didn't use them naughty me yet i just wanted to see how it went on a clean battery supply ,i didn't know about the oscillation problem with these transistors at those frequencies !

To be honest I would suggest a simple lo-noise op-amp, a LM833 or a NE5532, simpler and stable.

Steve A.


Yes i agree Steve these days we should use op amps i just have heaps for transistors and nice to be able to still use them for some thing and its something else you don't have to buy if you have something in the junk box .
As with you and valves i do like to try and use these for old time sake i might be a glutton for punishment but i enjoy soldering .
I will look into those opamps as with the Bistable chat and PWM so on many chats ago i do listen :wink: