LED matching
I have question about matching the LED's. I have tested now a batch of LED's and they all show a Vf of around 1.91V. Could this be a problem for the quintuplet string, which will be together 9.55V? Or should I find LED's with lower Vf to combine to end up closer to 9V? TIA
Joffrey
I have question about matching the LED's. I have tested now a batch of LED's and they all show a Vf of around 1.91V. Could this be a problem for the quintuplet string, which will be together 9.55V? Or should I find LED's with lower Vf to combine to end up closer to 9V? TIA
Joffrey
Builder Brad, for your reference if your considering Tent Labs you might want to check these guys out, much cheaper...
Dantimax (elektronik) - Kits
Dantimax (elektronik) - Kits
Transformer with low mains AC voltage
Hi Salas,
I am in the process of ordering transformers and will probably be using the 50VA 2x15V R core ones from this French company:
SELECTRONIC : Composants Electroniques, Systèmes d’Alarme, Matériel Electronique
only Question I have relates to my mains supply. I am using DIY balanced AC mains that drops to almost 200v when tested with a 60w light-bulb. here are some of the other tests that I did a few years ago on the kit that I was using back in 2007:
GK 1R V IN 227 V OUT 209
Arcam @8SE V IN 227 V OUT 211
Pioneer media box V IN 226 V OUT 207
Pioneer DVD 868avi V IN 228 V OUT 217
Sky+ satellite box V IN 227 V OUT 214
Orion power supply V IN 229 V OUT218
60 Watt light bulb V IN 231 V OUT 200
43 Watt light bulb V IN 227 V OUT 204
is it worth me using the 50VA 2 x 18v transformer in this situation?
Brad
Hi Salas,
I am in the process of ordering transformers and will probably be using the 50VA 2x15V R core ones from this French company:
SELECTRONIC : Composants Electroniques, Systèmes d’Alarme, Matériel Electronique
only Question I have relates to my mains supply. I am using DIY balanced AC mains that drops to almost 200v when tested with a 60w light-bulb. here are some of the other tests that I did a few years ago on the kit that I was using back in 2007:
GK 1R V IN 227 V OUT 209
Arcam @8SE V IN 227 V OUT 211
Pioneer media box V IN 226 V OUT 207
Pioneer DVD 868avi V IN 228 V OUT 217
Sky+ satellite box V IN 227 V OUT 214
Orion power supply V IN 229 V OUT218
60 Watt light bulb V IN 231 V OUT 200
43 Watt light bulb V IN 227 V OUT 204
is it worth me using the 50VA 2 x 18v transformer in this situation?
Brad
200Vac is way outside the 216Vac to 254Vac tolerance range for the UK.
The previous tolerance range, before harmonisation, was 240+-6%. Your 200Vac is even farther out than that.
Running 230Vac equipment from ~200Vac supply to me sounds wrong.
Can the DIY balanced AC mains supply be removed and binned? Or can it be modified to bring the output voltage inside the tolerance range for a UK supply?
The previous tolerance range, before harmonisation, was 240+-6%. Your 200Vac is even farther out than that.
Running 230Vac equipment from ~200Vac supply to me sounds wrong.
Can the DIY balanced AC mains supply be removed and binned? Or can it be modified to bring the output voltage inside the tolerance range for a UK supply?
As long as it fits, the 0.33 uf WIMA, shouldn't be a problem. Just a bypass cap.
Anand.
Hi Andrew,
I am not concerned with the UK mains spec, esp for this project as I can choose the other components in the rest of the build. That was the reason for asking the question. I was originally going to use SLA batteries on the B1 and am now looking at the AC supply. There is nothing to stop me plugging my B1 straight into the mains, but I have a very clean, balanced AC supply available and should really use that if I can. The voltage sag shown in my earlier post was when I powered a 60w light bulb. I would imagine that a 50VA transformer primary would put a very light load in comparison to the light bulb - probably more like the GK-1R load which has 2 similar spec transformers as the 50VA that is proposed for the B1, so I am probably looking at 210v worst case.
I really wanted to know if I should increase the B1 recommended transformer voltage values to allow for the lower AC input voltage that I am planning to use.
Brad
I am not concerned with the UK mains spec, esp for this project as I can choose the other components in the rest of the build. That was the reason for asking the question. I was originally going to use SLA batteries on the B1 and am now looking at the AC supply. There is nothing to stop me plugging my B1 straight into the mains, but I have a very clean, balanced AC supply available and should really use that if I can. The voltage sag shown in my earlier post was when I powered a 60w light bulb. I would imagine that a 50VA transformer primary would put a very light load in comparison to the light bulb - probably more like the GK-1R load which has 2 similar spec transformers as the 50VA that is proposed for the B1, so I am probably looking at 210v worst case.
I really wanted to know if I should increase the B1 recommended transformer voltage values to allow for the lower AC input voltage that I am planning to use.
Brad
cheers Salas,
I was thinking along the same lines. If I use a 230v primary 15v secondary transformer with a 210v AC supply I should get approx 13.5v on the secondaries. with the same supply voltage the 18v spec version gives me 16.5v. If I could find a 17v transformer I think that I would have a perfect fit.
The reason I asked in the first place was to see if the recommended specification at 15v had any flexibility ie. it was at it upper limits would work well with a slight voltage drop.
Brad
I was thinking along the same lines. If I use a 230v primary 15v secondary transformer with a 210v AC supply I should get approx 13.5v on the secondaries. with the same supply voltage the 18v spec version gives me 16.5v. If I could find a 17v transformer I think that I would have a perfect fit.
The reason I asked in the first place was to see if the recommended specification at 15v had any flexibility ie. it was at it upper limits would work well with a slight voltage drop.
Brad
Builder,
I recommend you look at three operational conditions.
When mains is at nominal UK voltage of 240Vac.
When mains is at 254Vac
When mains is at 226Vac.
Look at what happens to each component in the regulator for each of these three situations.
It might also be worth looking at what happens if you have your DCB1 with it's mains transformer connected directly to 254Vac instead of using the balanced voltage dropper.
Have you decided what CCS current you want to use?
The AC current rating of each winding must be at least twice the DC current you plan to draw and preferably four times your CCS currents.
I recommend you look at three operational conditions.
When mains is at nominal UK voltage of 240Vac.
When mains is at 254Vac
When mains is at 226Vac.
Look at what happens to each component in the regulator for each of these three situations.
It might also be worth looking at what happens if you have your DCB1 with it's mains transformer connected directly to 254Vac instead of using the balanced voltage dropper.
Have you decided what CCS current you want to use?
The AC current rating of each winding must be at least twice the DC current you plan to draw and preferably four times your CCS currents.
Another transformer question
Instead of the BOM specified 15-0-15V 50VA transformer recommended for the 200mA hotrod, is it possible to use a 12-0-12 V 48VA (or alternately 72VA) version instead? (reason is my local store carries only 12V versions, next step up are 18V variants).
For those who have tried both - are there any sonic benefits to using the 15V traffo over a 12V one?
Thank you for all the replies.
Instead of the BOM specified 15-0-15V 50VA transformer recommended for the 200mA hotrod, is it possible to use a 12-0-12 V 48VA (or alternately 72VA) version instead? (reason is my local store carries only 12V versions, next step up are 18V variants).
For those who have tried both - are there any sonic benefits to using the 15V traffo over a 12V one?
Thank you for all the replies.
Quite stable. Never seen it dip below 230VAC during the times I've measured/monitored it (typically 232VAC). Thank you Salas!