Note of the reed relays I have seen up to now is capable of withstanding 500+ volts across the open contacts. The clearance in most of them is usually far less than a mm.
Rundmaus
EDIT: I have to correct myself, just found this nice reed relay online. Sounds as if I am going to use it in some applications too.
Specifications:
LI 05-1A85 :: High Voltage Reed Relays LI
This LI-Series for PCB mounting provides contact between the coil and the largest air and leakage paths with the smallest possible design, whereby an isolation voltage of 4.25 kV DC is achieved.
Coil voltage: 5 VDC
Ri (typical): 200 ohms
Maximum switching power: 100 W
Maximum switching voltage: 1000 V DC / ACpeak
Switching / transport current: 1.0 / 2.5 A DC or ACpeak
L x W x H: 30 x 10 x 10.4 mm
Manufacturer : MEDER
Factory number : 1605185000
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Voltage drop on inrush current limiter is very low, you don't need relay capable of 400VDC.
And if you still want to use something for B+ delay for example, take high-voltage thyristor, solid state relay or opto-coupler.
Not this again... We've been through that.
GoatGuy and Rundmaus, interesting relay. I would have never have thought that type of isolation would be available in a reed relay. Now I have to figure out how they've accomplished that.
Reed Relay Magic
Given that I actually got to talk to a person who designed these things for the Space Missions in the 1970s... Several things:
[1] polished, rounded contacts
[2] high pressure krypton gas fill (10 atm or so)
[3] highly cleaned glass envelope, hermetic sealed
[4] 2 mm gaps
[5] contacts from low resistance graphite bonded to cobalt-nickel
[6] field magnet significantly "in" from the external reed terminals (many mm of glass insulation / isolation)
[7] high dielectric strength potting
[8] high dielectric strength "can"
Sounds like a lot, but in manufacturing, just a lot of tiny steps, easily put on an assembly line.
GoatGuy
Given that I actually got to talk to a person who designed these things for the Space Missions in the 1970s... Several things:
[1] polished, rounded contacts
[2] high pressure krypton gas fill (10 atm or so)
[3] highly cleaned glass envelope, hermetic sealed
[4] 2 mm gaps
[5] contacts from low resistance graphite bonded to cobalt-nickel
[6] field magnet significantly "in" from the external reed terminals (many mm of glass insulation / isolation)
[7] high dielectric strength potting
[8] high dielectric strength "can"
Sounds like a lot, but in manufacturing, just a lot of tiny steps, easily put on an assembly line.
GoatGuy
With the risk of sounding like a complete noob, I don't really understand what you mean with number [2], the two terminal regulator.
This haa developed into a VERY informative thread!
At [mouser.com] look for: IXCP10M90S
It has 3 terminals (the 2 terminal reference was a typo), but can be "treated" as a 2 terminal device, once the control lead is connected to the Gate is hooked to the Kathode via a suitably spec'd resistor. (When no resistor is used, it self-limits to 100 ma)
Very nice devices. Often used in "very modern" circuits for constant-current plate loads. Tolerates such high voltage (900V) that they are basically "universal parts" for the tube-loving forum. Let's hope the manufacturer never stops manufacturing them!
GoatGuy
It has 3 terminals (the 2 terminal reference was a typo), but can be "treated" as a 2 terminal device, once the control lead is connected to the Gate is hooked to the Kathode via a suitably spec'd resistor. (When no resistor is used, it self-limits to 100 ma)
Very nice devices. Often used in "very modern" circuits for constant-current plate loads. Tolerates such high voltage (900V) that they are basically "universal parts" for the tube-loving forum. Let's hope the manufacturer never stops manufacturing them!
GoatGuy
Yep. Though you know you actually only have 500uF of net capacitance there... Capacitors in SERIES are like resistors in PARALLEL (same equation C = (C1 C2)/(C1 + C2)). And the converse: when capacitors are hooked parallel, the capacitance simply adds (C = C1+C2). Have fun! Don't forget the *******' heat sink for the amazing constant-current regulator. Otherwise, it shall fry.
Yes, cool you noticed the reduction
. It was 1000uF in total, but after some redesigning (slightly lower HT) and new measurments, I decided I could do with half as well. Saves room and money.
for small reeds
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http://www.tme.eu/sk/Document/150598fa361ad54ce67865e103537193/h-10kv.pdf
i see high peak current
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regarding the peak charge current-it should be considered dcr parameter of secondary + choke.
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Unless the capacitors are fully charged I'd think it'll work. Otherwise, I still think the contacts will stick. It doesn't take much to exceed 3A. It'll be interesting to see how this turns out. That's still an impressive reed relay.
I think you meant "If the..." ... unless doesn't quite work! Nice thing about using the current-source is that you'd be able to sense when its across voltage had dropped to a constant trigger value indicating fullness.
GoatGuy
You are absolutely correct! "If the" is what I meant.
I once did that with a circuit that charged a 15F capacitor in my car. It was a current source using a BJT and once the voltage across it had dropped to less than a volt a timer waited a few dozen more seconds and then closed a 200A contactor.
The heat sink wasn't that big. I'm thinking that it was only an amp or two of charging current.
The manufacturer (most likely a re-seller) of the capacitor recommended just slamming the contactor shut at key-on. After seeing an 0 gauge cable jump from inrush I decided on devising soft start.
By the way, 15F didn't really make any noticeable difference in voltage stability. It helped with something like a bass drum, but not with anything sustained. It was no match for the 3 gel-cell batteries and the 10 amplifiers that they fed.
To be prepared for failure modes in a soft start circuit is always a good idea... Dealing with ac supply may have a direct impact on safety of your home ac supply, not mentioning possible electrocution or fire hazard... Even if you don't have to design to pass International regulations or National standard as CSA for you own project doesn't preclude to play safe.
Read this excellent website that discuss at large the subject of soft start and its related safety issues: Soft-Start Circuit For Power Amps
As you say in English, better safe than sorry.
Read this excellent website that discuss at large the subject of soft start and its related safety issues: Soft-Start Circuit For Power Amps
As you say in English, better safe than sorry.
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