my profile | my password | search | faq & rules | forum home

» Film-Tech Forum ARCHIVE   » Operations   » Film Handlers' Forum   » MPU-1 Could it be used for solar cells?

Author Topic: MPU-1 Could it be used for solar cells? Steven Cutting Film Handler Posts: 8 From: Kariong NSW AUSTRALIA Registered: Jul 2010 posted 06-06-2012 09:42 AM                     I have one of these and wondered if i could boost the signal of the cells to my cp50? Anyone tried it?  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 06-06-2012 10:29 AM                       The CP50 has a preamp intended to amplify the solar cell so why the need for boosting the signal? I'm thinking you have 2 35mm projectors using the preamp and you want to amplify a 16mm projector optical? The MPU can be used but it has way too much gain and is the wrong way to do it. It will work by reducing the level by putting a resistor across the input to the MPU on the solar cell wires. Around 500 Ohms if I recall.  |  IP: Logged Tony Bandiera Jr Film God Posts: 3067 From: Moreland Idaho Registered: Apr 2004 posted 06-06-2012 12:20 PM                     In addition to what Sam said I also ask why? 1: The EQ structure of the mag cards is not right for solar cells; 2: The gain as Sam mentioned is wrong; 3: If you can't get enough gain from the optical preamp card then you have a serious problem at the projectors' soundhead. Check the exciter lamp or LED alignment first. 4: Even for 16mm a CAT 108 has enough gain to work. For 16mm (or a mono cell) jumper the left and right (+) terminals to each other, do the same with the left and right (-) terminals. Then set the gain and HF pots to match. If for some strange reason you need extra projector inputs it is really easy to get a connector and wire up an outboard CAT 108.  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 06-06-2012 04:29 PM                        Are you running 16mm? If so, try a used Ashly BP-41 bass guitar preamp. (The best 16mm preamp ever made.) I sold 11 of them in Los Angeles for Academy screenings years ago. Dolby L.A. installed them in the DGA and other places. Louis  |  IP: Logged Steven Cutting Film Handler Posts: 8 From: Kariong NSW AUSTRALIA Registered: Jul 2010 posted 06-07-2012 05:40 AM                     Thankyou for your input gentleman. I have two 35mm raycophone rear scan projectors from I would say 1950's. They have nice soundheads with a prism that directs the light from a 10v 5amp lamp that I am running at full power. I have made do with a red filter for later type tracks. alignment is spot on and I have the cp50 set to high. I have an Sra5 Sr adaptor. All works well however I'm only just able to reach the dolby level with a test film, but the volume is lower with cyan soundtracks. If i crank the amps up it sounds poor. Looking for a cheaper alternative to red led readers. Thanks Regards Steve  |  IP: Logged Robert Minichino Master Film Handler Posts: 350 From: Haskell, NJ, USA Registered: Dec 2005 posted 06-07-2012 07:24 AM                        What are you using for a red filter? Do you know what its spectral transmission curve looks like? Incandescent exciters put out quite a lot of IR, and solar cells are quite sensitive to that, so if your filter isn't blocking the IR your signal/noise ratio on cyan isn't going to be very good (silver-applicated tracks block the IR). Louis's suggestion of the bass guitar preamp is a good one. I was going to suggest a mic-type preamp, but Louis's suggestion is even better.  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 06-07-2012 09:17 AM                        My thought is for 16mm MONO. A red herring! Louis  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 06-07-2012 12:15 PM                       Steve says. "If i crank the amps up it sounds poor. Looking for a cheaper alternative to red led readers". It will sound a lot worse if you use an MPU for a preamp booster, and then what? You hook it up to the solar cell input of the CP50? The MPU preamp is mighty hairball. There are many better ways to do this; the easiest is the Jaxlight which is a Red LED version of an exciter bulb. It can have its own set of issues but at least the red light produced is at the correct wavelength the cyan track wants to see. There are other threads here over the years describing some homemade RED LEDs replacing the exciter. Check them out.  |  IP: Logged

All times are Central (GMT -6:00)

Printer-friendly view of this topic

Hop To: Select a Forum: Category: Operations -------------------- Digital Cinema Forum Film Handlers' Forum Large Format Forum Ground Level Feature Info, Trailer Attachments & REAL Credit Offsets Category: Community -------------------- Film-Yak Film Handlers' Movie Reviews The Afterlife Bob Maar's Joke-A-Thon Category: Classified -------------------- Equipment and Supplies Wanted/For Sale Help Wanted/Seeking Employment Category: System -------------------- Software Beta Testing Forum

The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion and agrees to release the authors from any and all liability.