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| Digibees DB800 Synch Voltage https://paulcbuff-techforum.com/viewtopic.php?f=8&t=4986 |
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| Author: | GHWanner [ Tue Nov 08, 2016 10:05 am ] |
| Post subject: | Digibees DB800 Synch Voltage |
I recently purchased a DB800 for use with my Canon 5DSr and associated Canon flash equipment. The unit works perfectly; synch using a Canon ST-E3-RT transmitter and Yongnuo YNE3-RX receiver is perfect at 1/200 second (max synch speed on the 5DSr). No shading or black bars visible over the full range of DB800 flash power. Being a curious electrical engineer, I measured the synch voltage with a Fluke 289 digital voltmeter, which has a 10 MOhm input impedance. The measurement was just over 10 volts, whereas your specs indicated a synch voltage of ~5 volts. Why the difference? Thanks, Gus |
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| Author: | Technical Support [ Tue Nov 08, 2016 4:46 pm ] |
| Post subject: | Re: Digibees DB800 Synch Voltage |
You are correct – the maximum measurable voltage is 10v. This can only be measured in the manner you are describing, with a very high impendence circuit. When you start accounting for other components in the system, such as the sync cable itself, connectors, etc. this voltage will decrease as the impendence is reduced. More importantly, the actual energy storage of this supply is only 10uJ, and it is fully isolated from the rest of the unit. |
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| Author: | GHWanner [ Wed Nov 09, 2016 9:54 am ] |
| Post subject: | Re: Digibees DB800 Synch Voltage |
Thanks for your quick response. However, I must respectfully disagree with your statement that synch cables and connectors will affect the synch voltage, since their DC parallel resistance is essentially infinite at the 10 volt level applied. As an example, I measured the parallel DC resistance of the synch cable included with the Digibee using a Megger Insulation Tester. With 50 volts DC applied, the resistance between the synch cable conductors measured ~5 Gigohms (e.g. 5x10^9 Ohms). Such a high resistance will obviously have no effect on the synch voltage. The only thing that would reduce the "open circuit" synch voltage is the parallel DC resistance of the camera (or remote receiver) synch switching circuitry, which must also be very high to avoid spurious triggering. In any case, though not a big deal, your specification for the Digibee synch voltage would be more accurate if you stated "approximately 10 volts" rather than "less than 6 volts". Best regards, Gus |
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| Author: | Technical Support [ Fri Nov 18, 2016 11:53 am ] |
| Post subject: | Re: Digibees DB800 Synch Voltage |
For clarity, this discussion in routed through the engineering department. We agree that those parallel resistances should not be significant with respect to the 10MOhm (unless the insulation was somehow compromised). We measured about a 1V drop when the 10MOhm load was replaced with a 1MOhm load. It is also worth noting that the nominal voltage does vary from unit to unit – the unit we measured had a voltage of 9.12V across the 10MOhm load, which is caused by variations in the opto-isolators being used to generate this potential. Thanks for your feedback, we’ll ask our marketing department to revise the specification. |
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| Author: | GHWanner [ Tue Nov 22, 2016 11:02 am ] |
| Post subject: | Re: Digibees DB800 Synch Voltage |
Thanks for your response to my comment. Your measurement of a 1 volt drop (e.g. ~9 volts) with a 1 meg Ohm load agrees with my measurements. Thanks for designing an outstanding strobe at a great price! |
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| Author: | craig16229 [ Fri Nov 25, 2016 5:30 pm ] |
| Post subject: | Re: Digibees DB800 Synch Voltage |
Tech Support - in the scenario that the OP describes, what consideration/issue does the variance he measures create? I am not an electrical engineer. Could it affect latency and getting the absolute maximum X-sync? Thanks, Craíg |
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| Author: | Technical Support [ Tue Nov 29, 2016 4:44 pm ] |
| Post subject: | Re: Digibees DB800 Synch Voltage |
There is no differences in latency. There could be a theoretical incompatability, but we have yet to see any issues from it. |
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