mattthegamer463

Yes but that's not what the circuit shows in the image you posted. It shows it cannot connect to the 9v as they are on opposite sides of a SPDT switch.This should not be hard to solve by tracking the resistance along the circuit using your meter.

It's a current limiting resistor for the lamp. The old 1/21 used a bigger 1.5V cell but the LR44s in the Spotmeter V can't even supply more than 150-200mA in a dead short, so the 5W power rating is absurdly oversized. This resistor is only to control the brightness of the bulb. Maybe the 1/21 used a 1.5v bulb and they wanted to dim it. Another option they could use would be to use a higher voltage bulb so that it would be naturally much dimmer by being undervolted.I doubt this resistor has failed, if there is a similar or equivalent one in the V. There is no power available to burn it out, only physical damage or vibration could cause it to fail.

Just try it. Look into the viewfinder snd see if it looks good in dim light. A bright bulb could mess up the readings.

I don't think I touched those. My light did work briefly but stopped shortly after and I never tried to fix it. I think those are capacitors with colour coded values. If you google you should find a guide on how to read the values. Unless they are mechanically broken, I wouldn't expect them to be bad. Ceramic caps are pretty hearty.

If it is a steady 178 ohm, you may be right. It could also be a cap with a resistor in parallel. I don't know why a thermistor would be used in this application for the lamp. It doesn't make a lot of sense to me. Again, with such limited voltage and power from coin cells, why would the thermistor fail? Try warming it up and see what the resistance does. When you observe the full brightness of the bulb, is the bulb assembled in the meter body? Maybe the bulb is supposed to be dim. It's only trying to light the tiny scale when in the dark, a super bright bulb isn't needed and would deplete the battery quickly.

Maybe the bottom side of the contact is corroded and needs cleaning.

If you can find something that will fit, I'm sure it would work.

I think you will need to use a volt meter to trace the voltage from the button contact area to the bulb, to see what is going on. You should be able to see where the battery + connection comes in on the long PCB that is near the bottom of the meter, and follow the traces and wires to the button contacts, and see what is going on using the volt meter.

I think ideally you should fix what's there. It must be something simple. Test the continuity with a resistance meter to find the part of the circuit that isn't behaving as expected.

Could be a 6v running on 4.5v to make it less bright than the manufacturer intended.

I think so. That kind of looks like the bottom of a light bulb with the centre pin soldered to that wire. Test the resistance before dismantling as the bulb may be fine and your button contacts may just need adjustment or something. The battery power is so low it would be hard to burn out that bulb, I would think.

I think so. That kind of looks like the bottom of a light bulb with the centre pin soldered to that wire. Test the resistance before dismantling as the bulb may be fine and your button contacts may just need adjustment or something. The battery power is so low it would be hard to burn out that bulb, I would think.

Hi Christophe, you'll have to forgive me, I wrote this 7 years ago and haven't opened the spotmeter again since. I would assume that spring is some kind of switch contact, otherwise it would just be a connection through the circuit board. Is there an external button that would touch it?I'm not exactly sure where the bulb is because I never dismantled it beyond what you see in the photos. I think the bulb wires are the twisted pair of yellow wires that run from the bulb button contact patch up to near the top. I would check the resistance across those two wires, you should expect a couple hundred ohms if the bulb is good, and infinity if it is burned out.

It's a threaded ring, basically a large diameter smooth nut. I didn't have a lens wrench or snap ring pliers big enough so I showed a trick to undo it without being able to bridge both of the holes in the ring. If you have a lens wrench with pointed tips that would work well.

Yes that is the kind of thing that works well for large diameter threaded rings.

Hi Christophe, I think it is a 6v bulb. I suspect the failure is the small button contacts. My own unit worked only sporatically. The bulb is under the scale, slightly above and behind the trigger. It would probably be easier to replace with a LED, easy to run on 6v with a resistor.

If you can't make your own upper wheel it will be cheaper to go Harbor Freight, for sure. This was almost 10 years ago and the top wheel was pretty cheap, now they are a lot more.

Hey there, on the label it is marked as "Custom R", the idea being you can put whatever you want there. You could put 10M in there if you wanted another decade of range.

If you think you can do it, I can give you tips. I can't help you actually build it.

Thanks for the comment. The knobs are common electronics knobs, designed to fit a 1/4" shaft. The shaft that engages the film spools was made by me out of 1/4" aluminum. The knobs fit with no trouble and by pushing them tight and then tightening the locking screw, they keep a little bit of friction and keep any gaps closed, for light resistance.There aren't any thumbscrews with springs. The back is held on by nuts like these, and 1/4-20 threaded studs. https://www.mcmaster.com/92741a160

Step 1 has a closeup picture of the final design with some dimensions.

There are many 7800 series regulators available from many manufacturers and suppliers. Just do a search and you'll find lots

Yes you can change the design for 35mm. Glad you liked it.

I think that should be possible, however measuring the curtain speed would be tough, unless you are doing something like starting at "0" and detecting the start and end of each sensor detection, that would tell you the opening and closing time. I don't think you'd get that information just measuring the duration that each sensor is detecting the shutter to be open, but that would detect "shutter capping" and the change in shutter slit width from start to finish, like you describe below.

Mine doesn't work well either. I would try cleaning and adjusting the contacts for that little button. While it is apart, double check that it is working properly and that the bulb isn't burned out.

The lamp only illuminates the scale when the room is dark. It doesnt change meter performance.

nice work, a great looking build. much nicer wiring and the point to point construction is definitely a good choice.

Thanks for your comment, I'm glad things are working well for you and that I was able to teach you something.

You're right, so I added a bold and capitalized paragraph warning people of the dangers of working with electricity without precautions.

Yes that will work, just omit the transformer, bridge rectifier, and reduce the large capacitors from 10kuF to 100uF. Also use 7809 regulators.

It was done in Sketchup, I've added a file to Step 1 https://www.instructables.com/files/orig/F7N/DBHB/JDF28X4C/F7NDBHBJDF28X4C.skp

Hi, I know what you mean about that. Modern LEDs are multiple junctions inside a single package which results in odd shapes. The best way to handle this is to put a small piece of diffusion material over it. Just enough to change the shape back to round and spread some of the light out so there aren't any bright patches, although that may not be a big issue. The real issue is the shape.If you can cut a piece of plastic or something to cover it, that would work.If you want to drop to a weaker LED, look for ones that are rounded and have a cloudier interior that prevents you from seeing the junction clearly. https://www.aliexpress.com/item/10PCS-1W-3w-High-power-led-pure-white-warm-white-cool-white-Factory-wholesale-Free-Shipping/1676224972.htmlDoing this project with three high power …

Hi, I know what you mean about that. Modern LEDs are multiple junctions inside a single package which results in odd shapes. The best way to handle this is to put a small piece of diffusion material over it. Just enough to change the shape back to round and spread some of the light out so there aren't any bright patches, although that may not be a big issue. The real issue is the shape.If you can cut a piece of plastic or something to cover it, that would work.If you want to drop to a weaker LED, look for ones that are rounded and have a cloudier interior that prevents you from seeing the junction clearly. https://www.aliexpress.com/item/10PCS-1W-3w-High-power-led-pure-white-warm-white-cool-white-Factory-wholesale-Free-Shipping/1676224972.htmlDoing this project with three high power RGB lasers, mixed with a prism into a white beam and then spread by a lens into a wide beam would be a neat way to do this project now, I think. I don't know if it would work but I think it could. The lasers going through the pinholes may cause weird interference patterns and would look neat but not look like stars. Also diffraction through the pinholes may cause rainbow stars instead of white stars.

your voltage is too high I think. follow the listed specs for the LED or it won't last long. Try a 1W or try to diffuse the brighter LED further. Cree makes some tiny high power LEDs which may work for you as well. It's a tough problem.

This is great. I thank you for using a design that doesn't hurt the camera.I once tried to make a motorized slit scan camera from a broken pentax SLR and failed due to a number of issues with the mechanisms, but I never thought to wind the film backwards instead of forwards. It's a much better idea and is so much simpler. Thank you for the genius spark that can get me back to that project.

In retrospect I wish I had done something more along those lines. It would have simplified and made a much better final product. Live and learn.

Do you find the across the 6" length of the tubing is flat? I want to do this as well but I am worried the tubes are not rectangular but slightly "crowned" which would cause a part to rock side to side if placed on just one tube.

thanks for sharing

you're right, there is an error there. the photodiode output goes to pin 21.

I would recommend you try to figure out a way to make a new drum for a off-the-shelf music box mechanism. A little one like this; http://www.blokeystuff.com.au/ProductImages/838310...The way I built mine is not applicable at the traditional music box mechanism scale. Possibly you could drill very small holes in a metal drum and insert small pieces of steel wire, but it would be precision machining work. Possibly it could be 3d printed, with tiny holes for the steel wire "notes".

in testing it appeared to work fine. the spring is strong enough to be useful but not too strong to overpower the timer. The timer didn't seem to run fast from pressing the handle so I tried it. when wound halfway it ran for the prescribed half hour, and works to track stars.

Can you explain what you mean further? I don't believe the spring has any effect on timing

I would recommend finding a small slow moving motor like one from a microwave for the turntable inside. those usually run about 5-6 rpm. Using a motor like that to make a rotating base would make all the projections rotate. to selectively obscure some, i would make the projector stationary and use that same motor to rotate a large upside down bowl over top of the projector. cut a slot in the bowl as big as you need to let the light through. somehow youll have to make a platform that would let the bowl rotate but not the projector, which is not that easy with a simple motor. youll need to make it very bright for it to be seen in a big room with other lights on.hopefully that gives you some ideas to get going.

It's part of the utilitarian aesthetic of Tom Sach's work.

All I saw was the thumbnail and instantly knew who that was supposed to be. I'd say that's a pretty good sign of success. Great job.

You can connect more matching batteries in parallel with the original battery to increase the battery life.

Sorry I can't think of anything that would improve battery life. The hack should not result in a change in battery performance.

frankly I don't understand a lot of your questions. If you elaborate maybe I could help. The tines in those music boxes deflect very little and are plucked by small and short nibs on the drum. acrylic will probably be too weak.

if you're talking about the little hand-cranked ones, I think what is happening is there are vibrating tines in the base, and they are made to vibrate all the time by the cranking movement, but a metal wheel sits on the tine and stops it from making sound. When the hole in the paper comes by, the wheel can lift up slightly into the paper hole, which allows the note to ring for a moment. Slots in the paper allow for longer notes. This is my guess based on the pictures I can find.

I agree, 0.3A is very low. I would not use something so low next time. I haven't had any issues with it though, running several pedals. The thing is, it can deliver more than 300mA, but the voltage at the transformer secondary may drop lower than 18V AC, but there is a lot of voltage headroom in the design.There's really no chance for an issue until the transformer overheats to the point of failure, which would take some doing.

Nice work. Glad it was helpful for you. If you can make room for a bigger fan, that would help make it quieter.

Can you explain more?

I attached some PDFs I found, might be useful for you.

I attached some PDFs I found, might be useful for you.

I attached some PDFs I found, might be useful for you.

Or just adjust the ISO to compensate.

Looking at my pictures, I count 4 potentiometers total. I imagine there could be high/low sensitivity or limit setting pots, but I suspect the one near the metal can (which I believe is an operational amplifier) could be a gain-adjust. I suggest tuning that one until you have linearity in readings, then adjust the others to try to get the right values at high and low EVs. If this is just for you and your linearity is fine but the reading is simply off, maybe identify the error and mark it on the unit so you can do quick math in your head? ie. adding 1/2 an EV to each reading to correct for the error.

Hi John, looks like you did a fantastic job on it. I'm glad to hear you managed to make use of the information I provided.