0-30V可调稳压电源电路
DIY日记0-30V可调线性稳压电源
DIY日记0-30V可调线性稳压电源DIY日记——0-30V可调线性稳压电源啊哲作为一名电子爱好者，平时喜欢做一些电子小制作，在电路调试和制作过程中经常为电源犯愁，有时候为了调试一个简单的电路而单独搭一个电源，这样即费时又消磨DIY的兴致。
最近本人利用手头一些闲置零件，自己打造了一台“MINI”型直流0-30V可调稳压电源。
现将整个DIY过程与大家分享。
（图1）本人在深圳工作时买了几个大小不一的铝合金外壳（当时看到这些外壳挺漂亮就买了，一直闲置着），其中一个较大一点的外壳尺寸为：134x106x55mm。
家里还闲置了一个功率约30W左右的小变压器（该变压器是从旧黑白电视机上拆下来的，有8V和18V两组输出），其厚度还刚好能装到这较大尺寸的铝合金外壳内。
既然这么巧合，想不“撮合”它们都找不到理由了。
那接下来就是考虑稳压电路部分了，0-30V可调稳压电路可以通过以下几个方案来实现：1)采用运放加大功率管来实现（市面上很多批量生产的可调稳压电源都采用这种方案），该方案使用的材料非常低廉，但线路复杂不适合手工搭板；2)采用LM723专用电源稳压IC加大功率管来实现，该方案比较成熟，线路也比较简单，但LM723比较难买，需要到电子市场去找或邮购；3)采用LM317/338电源稳压IC，该方案线路非常简单，但按其典型应用电路接法，输出最低只能调到1.25V，要想0V起调必须加一个稳定的负电压基准来修正，一些电子杂志上也有人在LM317输出端串联2个二极管来降压，达到调“0V”的目的，这是初学的菜鸟们讨论的问题，大家心知肚明就行了；4)采用TL431电源稳压IC加大功率管来实现，该方案也具有线路简单的优点，但也同样遇到LM317不能调“0V”的问题；5)采用LM2576-ADJ开关型稳压IC来实现，该方案也具有线路简单、效率高等优点，但也同样遇到输出不能调“0V”的问题和电感线圈比较难加工；通过一番权衡利弊后，决定采用LM317的方案，刚好手头还有几个闲置的LM317T，“量身”设计的完整电路如图2所示。
电子爱好者必备工具——0-30V稳压可调电源DIY
电子爱好者必备工具——0-30V稳压可调电源DIY上次开贴准备在群里收集一些关于0-30V3-5A的稳压可调电源电路图，好象没什么人关心，通过这些时的收集，通过各种手段，看别的论坛，网上收收集，还包括购买，验证，纠错等，找到了一些电路图。
现在献给我一样需要的朋友们，我会陆续公布所做的电路及实图，希望感兴趣的朋友一起参与。
搞电子制作，特别是调试过压欠压，过载，过流等需要有可变值的各种电压，为了保护做的电路还得需要有一定保护措施的带保护，带恒流的稳压电源就尤为重要了，有的人会说买一台，只两三百块钱，当然这是最好的，简单快捷，也许还便宜，但这话就不要在这里说了，在这里讨论这个也是为了搞清楚原理及增强自已动手的能力，重在制作的过程其中的乐趣只有自已知道。
还是先易后难开始，下面这款LM317扩流电路简单，总计元件才十个左右，如果增加调整管，电流可以达到扩大到你想要的目标！我所见的很多UPS上用的都是LM317，看来片可调稳压IC是经得起考验的根据这个电路搭成的电路板如下：用这个电路试验了几次，稳压精度对于我们一般的大多数人业余DIY足够了，稳定性也不错。
当然这个电路是基本电路，只有简单的过流和短路保护也只能从1.25V起调，如果想从0V起调，还得加一个负压电路了，不仅如此，不能恒流，也不能保持较小的压差，减少功耗，为此还得进行改进！主要元气件参数资料：尽管LM317我们已经非常熟识了，但还是翻阅一下LM317的PDF资料比较稳妥，其中几个比较重要的参数如下：1、输入与输出端最高压差为：40V（很多人误认为是输入最高电压为40V）；2、输入与输出端最小工作压差：3V；3、输出电压范围：1.25V-37V范围内连续可调（其实只要保证前一项条件，其输出范围的上限是可以扩展的）；4、最大输出电流：1.5A（LM317T TO-220封装）；5、输出最小负载电流：5mA；6、基准电压VREF：1.25V；7、工作温度范围为：0-70℃；8、 LM317T TO-220封装引脚排列如图3所示：为了让LM317T输出0V起调，该电路设计时增加了一个由TL431构成的-2.5V基准电源，TL431相信大家也是非常熟识，它是三端可调并联型稳压IC工作原理：如图2所示，220V市电通过S1和F1连接到变压器的输入端，经过变压后分别输出：18V、8V、10V、3V（其中10V和3V绕组是自己以手工穿线的方式加绕的）四组电压，为了降低LM317T的功耗提高电源效率，采用了2个继电器的3级换档电路，换档电路如图6所示，电源输出电压V+加在W2的两端，当W2的滑动触片上获得的分压低于U4的VREF（2.5V）电压时，U4的K、A之间只有微弱的维持电流，J1因得不到足够高的工作电压，其常开触点断开，8 VAC绕组通过J1和J2的常闭触点对后级电路供电；当W2的滑动触片上获得的分压高于U4的VREF（2.5V）电压时，U4的阴极电流剧增使J1得到足够工作电压，其常开触点吸合，18 VAC绕组通过J1常开触点和J2的常闭触点对后级电路供电。
直流稳压电源设计报(0-30V,调节)
模拟电路课程设计报告设计课题：专业班级：学生姓名：指导教师：设计时间：目录1．实训目的┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈2．设计任务与要求┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈2.1.需用仪器、仪表┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈3．方案选择与论证3.1课题分析3.2稳压电路方案选择3.3分立元件串联型稳压电路3.4集成稳压块稳压电路4. 单元电路设计与参数计算4.1桥式整流电路4.2滤波电路4.3稳压电路5.总原理图及元器件清单5.1总原理图（含元件标号与型号）5.2元件清单6. 安装与调试6.1仪器、材料的准备6.2单元电路安装与检测6.2.1变压器的检测安装6.2.2整流电路的安装与检测6.2.3滤波电路的安装与检测6.2.4稳压电路的安装与检测7.性能测试与分析7.1主要技术指标的测试8.器件清单9.结论与心得10.参考文献直流稳压电源设计报告1．实训目的2．设计要求设计并制作一个带过流保护的串联式稳压电源。
主要技术指标为：（1）输入交流电压；（2）输出直流电压；（3）额定输出电流；（4）稳压系数；（5）电源内阻；（6）纹波电压；（7）具有工作指示。
2.1需用仪器、仪表:3．方案选择与论证3.1课题分析3.2稳压电路方案选择3.3分立元件串联型稳压电路3.4集成稳压块稳压电路4．单元电路的设计4.1桥式整流电路（1）整流电路的结构原理图3-2 分立元件稳压电路图4- 1桥式整流电路及输出波形（2）主要元件选取与参娄计算桥式整流电路主要参数计算公式：4.2滤波电路（1）滤波电路的形式图4- 2桥式整流C型滤波电路及其输出电压的波形滤波电路的输出电压与滤波电容有关，一般取：U O =（0.9 ~ 1.4）U i（2）滤波电容的选取4.3稳压电路（1）电路形式通过滤波电路输出的直流电压比较平滑，但还是会随交流电网电压的波动或负载的变动而变化。
0-30V任意值可调电源供应器制作
0-30V任意值可调电源供应器制作概述这是一种高质量的连续可变输出稳定在0和30VDC之间的任意值可调的电源。
该电路还采用了电子输出电流限制器，可以有效地控制输出电流从几毫安(2毫安)三安培，该电路可提供的最大输出。
这一特点使得在这个电源中不可缺少的，因为它是可能限制电流典型最大，可能需要根据测试电路，电源，然后没有任何担心，它可能会损坏，如果出现错误。
还有一个限流操作，使你可以看到你的电路是超过或不预设限制一目了然的视觉指示。
技术规格-特点技术规格输入电压：................24VAC输入电流：................3一个(最大)输出电压：.............0-30 V可调输出电流：.............2一个可调输出电压纹波：MA-3......最大0.01%特点-减少了尺寸，施工方便，操作简单-容易调节的输出电压-输出电流限制与视觉指示-防止过??负荷和故障提供的设备的完整保护。
它是如何工作首先，有降压电源变压器次级线圈与额定24V/3A，这是整个电路的输入点连接在引脚1和2。
(耗材输出的质量，将变压器的质量成正比)。
变压器次级绕组的交流电压整流桥由四个二极管D1?D4组成。
采取跨桥的输出直流电压平滑储能电容C1和电阻R1组成的过滤器。
该电路采用了一些独特的功能，这使得它完全不同于其他同类的电源不同。
而不是使用一个变量反馈的安排，以控制输出电压，我们的电路使用一个常数增益放大器提供参考电压，其稳定运行的必要。
U1输出的参考电压产生。
该电路工作过程如下：二极管D8是一个5.6V齐纳，在这里经营的零温度系数电流。
在U1输出电压逐渐增加，直到二极管D8是开启。
当这种情况发生电路的稳定和齐纳参考电压(5.6 V时)通过电阻R5出现。
通过运算放大器的非反相输入的电流流动是微不足道的，因此，通过R5和R6的电流流过，两个电阻具有相同的值跨越他们两个系列的电压将完全两倍每一个两端的电压。
0_30V_0_30A可调开关稳压_恒流源
Ｄ０３、Ｃ０３、Ｒ０５为散热风扇Ｆｓ提供电力。输出功率越大，风扇转速越高。供电变压器 为５Ｗ变压器，为减小体积亦可用小型开关电源供电。数字显示表头供电需用稳压电源。 本机在测量功率元件方面极为实用，只需将二极管、三极管、场效应管、ＩＧＢＴ、可 控硅等元件按极性接入“＋”、“－”输出柱上，饱和触发后，由小到大调节电流钮， 即可分别在电压表和电流表上同步观看到被测元件任一电流对应的压降值，可速测不明 功率元件，甚至包括保险丝、金属线的工作电流能力、导通压降等重要参数，也易于鉴 别虚假标号的元件。 本电路特别适合制作大功率逆变电源。笔者曾用其原理设计过１００Ａ可调恒流源，１２ ～２４Ｖ ５００Ａ电解电源等多款产品，性能令人满意（有关货讯见本期中缝）。 □广州 翟东波
笔者经多年实践设计了一种串联推挽电路，该电路主体似桥式，而推动电路又似推
挽，集二者优点于一身，从应用实践来看，该电路制作容易，性能稳定可靠。下面介绍
一种应用实例，分别见两电路图。
ＩＣ１（ＳＧ３５２５Ａ）为近年流行的双端集成电压控制器，工作频率可达２００ｋＨｚ以上，本 例采用３５ｋＨｚ。通电后，交流经Ｃ１、Ｌ０１、Ｌ０２、Ｃ２、Ｃ３、Ｃ４滤去干扰、ＤＬ整流、Ｃ５滤波储 能，作逆变回路主供电。Ｒｔ为负温度系数热敏电阻，用以减小开机瞬间ＤＬ的电流冲击， Ｒ１１、Ｒ１２及Ｒ１３、Ｒ２８为Ｃ６、Ｃ７的均压电阻。 当ＩＣ１⒁脚为高电位时，Ｍ点也为高电位，脉冲电压一路经Ｃ１４、Ｒ１４加至Ｑ６栅极，Ｑ６导 通；另一路将Ｃ８电容正端电位抬高，使其由原来的１／２ＶＥ升高为１／２ＶＥ＋１８Ｖ，经Ｒ１８加到 Ｑ５栅极，Ｑ５导通。变压器Ｂ１初级线圈Ｌ１、Ｌ２同时导通，次级线圈Ｌ５感应电流由Ｄ０１整流输 出。同理，当⑾脚为高电位时，Ｑ８、Ｑ７同时导通，初级电流流过Ｌ３、Ｌ４，次级感应电流经 Ｄ０２整流输出。 由于Ｑ６、Ｌ２、Ｑ８、Ｌ４在下１／２ＶＥ区交替导通，Ｑ５、Ｌ１、Ｑ７、Ｌ３在上１／２ＶＥ区交替导 通，相当于两个推挽电路上下串联使用，故笔者称其为串联推挽电路。尽管此电路变压
30V低成本连续可调直流电源电路
这里介绍的可调直流稳压电源可以实现从1.25V~30V连续可调，可调直流稳压电源输出电流可到4A左右。
她采用最常见的可调试稳压集成电路W317组成电路的核心，关于可调直流稳压电源的详细指标参数可参阅这里。
下面简单介绍一下该可调直流稳压电源电路的特点。
本可调直流稳压电源电路中，由T2、D5、VW1、R5、R6、C10及继电器K构成自适应切换动作电路。
当输出电路低于14V时，VW1因击穿电压不够而截止，无电流通过，T2截止，K不吸合，其触点K在常态位置，电路输入电流14V交流电。
反之当输出电压高于14V 时，VW1击穿导通，T2亦导通，继电器K吸合，28V交流电接入电路。
这样可以保证输入电压与输出电压差不会大于15V，此时，W317输出电流典型值为 2.2A。
图中采用了两块W317供电，整个电路输出电流可在4A以上。
由于两块W317参数不可能一样，可调直流稳压电源电路中在W317输出端串接了小阻值电阻R3、R4，用以均分电流。
可调直流稳压电源输出电压调整由RP1、RP2完成。
附加晶体管T1的目的在于避免电位器RP1滑动端接触不良，使W317调整公共端对地开路，造成输出电压突然变化，损坏电源及负载。
可调直流稳压电源双色发光二极管作为保险丝熔断指示器（红光）兼电源只是器（橙色光）。
当电源正常时，两只发光二极管均加有正向电压，红、绿发光二极管均发光，形成橙色光。
当保险丝FU2断开时，仅红色发光管加有正向电压，故此时只发红光。
以保证稳压准确。
设计电路板时主电流回路应足够宽，并焊上1mm以上的铜导线或涂锡，以减少纹波电压。
C6、C8尽量靠近W317的输入、输出端，并优先采用无感电容。
C5如无合适容量，可用几只电容并联。
R3、R4可用锰丝自制。
可调直流稳压电源调试时，调整RP1、RP2应使继电器在电源输出14V左右时吸合，否则可调换稳压二极管再试。
0-30V可调电源DIY详解
DIY日记——0-30V可调线性稳压电源啊哲作为一名电子爱好者，平时喜欢做一些电子小制作，在电路调试和制作过程中经常为电源犯愁，有时候为了调试一个简单的电路而单独搭一个电源，这样即费时又消磨DIY的兴致。
最近本人利用手头一些闲置零件，自己打造了一台“MINI”型直流0-30V可调稳压电源。
现将整个DIY过程与大家分享。
（图1）本人在深圳工作时买了几个大小不一的铝合金外壳（当时看到这些外壳挺漂亮就买了，一直闲置着），其中一个较大一点的外壳尺寸为：134x106x55mm。
家里还闲置了一个功率约30W左右的小变压器（该变压器是从旧黑白电视机上拆下来的，有8V和18V两组输出），其厚度还刚好能装到这较大尺寸的铝合金外壳内。
既然这么巧合，想不“撮合”它们都找不到理由了。
那接下来就是考虑稳压电路部分了，0-30V可调稳压电路可以通过以下几个方案来实现：1)采用运放加大功率管来实现（市面上很多批量生产的可调稳压电源都采用这种方案），该方案使用的材料非常低廉，但线路复杂不适合手工搭板；2)采用LM723专用电源稳压IC加大功率管来实现，该方案比较成熟，线路也比较简单，但LM723比较难买，需要到电子市场去找或邮购；3)采用LM317/338电源稳压IC，该方案线路非常简单，但按其典型应用电路接法，输出最低只能调到1.25V，要想0V起调必须加一个稳定的负电压基准来修正，一些电子杂志上也有人在LM317输出端串联2个二极管来降压，达到调“0V”的目的，这是初学的菜鸟们讨论的问题，大家心知肚明就行了；4)采用TL431电源稳压IC加大功率管来实现，该方案也具有线路简单的优点，但也同样遇到LM317不能调“0V”的问题；5)采用LM2576-ADJ开关型稳压IC来实现，该方案也具有线路简单、效率高等优点，但也同样遇到输出不能调“0V”的问题和电感线圈比较难加工；通过一番权衡利弊后，决定采用LM317的方案，刚好手头还有几个闲置的LM317T，“量身”设计的完整电路如图2所示。
30VDC3A恒压恒流直流可调稳压电源
30V/3A 恒压/恒流直流可调稳压电源电路特点(1)数字电压表电压上图电流显示，显示精度0.1 V上图0.01A(2)过流保护功能，限制电流通过电流表设置。
即具有恒流功能。
此功能在维修、调整有短路故障的电路时可以防止电流过大而烧毁线路板或稳压电源本身。
(3)具有自动风扇控制电路，电源调整管散热片超过55℃时自动启动散热风扇。
工作原理主电路：图1由1M31 7、Q1、Q2组成。
是1M31 7的典型扩流应用电路。
未采用目前流行的大功率稳压集成电路1M338,是因为它的过流保护功能太灵敏，瞬间超过5A即进入保护状态，而小型电动工具(如小电钻、直流电机)的启动电流往往超过5A且不能带感性负载，这一点我已经试验过。
电流表取样电阻R6如果采用康铜丝绕制，由于阻值太小，即使事先用电桥精密测好，加上接点(焊点)电阻也会超出误差范围。
这里采用0.12Ω水泥电阻，电流产生的压降经RP3调整后送至满度为2V 的电压表头，电流满度为20.00A。
控制电路如图2所示。
恒流控制电路由电压比较器1M393的一个比较器构成，RP4为电流调整电位器，由IC5产生的精密电压基准(约2.5-2.6V)经RP3分压后送至IC6的反相输入端。
由RP4分压后产生的电流取样电压送至IC6的同相输入端。
如果实际电流超过设定的恒流值，IC6输出高电平，Q4导通，1M317调整端电位下降→输出电压下降→输出电流下降，直至实际电流等于设定电流值。
同时Q3导通，发光二极管VD6显示处于恒流状态。
短路保护功能：1M317本身具有完善的保护功能，但输出短路时并不能保护扩流功率管。
短路时输出电流远大于设定的电流值使Q4完全导通，1M317的输出为最小值(约1.2V)此时实测显示的短路电流值约4-5A。
虽然限制了短路电流，但由于扩流功率管的耗散功率较大，时间长还是有危险最好加装输出短路保护保险管(5A)。
J2为电流设置/显示转换继电器。
处于1位置时，电流取样电阻R6的压降经RP3调整后送至电流表，显示当前的实际电流。
0-30V稳压电源最新说明
0-30V 可调电压、电流稳压电源安装使用说明书这是一个高品质的连续可调稳压电源，电压调整范围为0-30V，还包含了一个电流输出限制电路，有效地控制最大输出电流从 2毫安到3安连续可调，这个特色让这个稳压电源成为电路实验不可或缺的利器，它可以把电流限制在实验电路的典型最大工作电流，大胆地开启电源，不用担心因故障或安装错误造成大电流破坏实验电路。
技术规格：输入电压：24V 交流（最大）输入电流：3A（最大）输出电压：0-30V 连续可调输出限制电流：2mA-3A 连续可调输出电压纹波：0.01%（最大）电路特点：全部直插元件，安装、维修简单方便；输出电压易于调整；输出电流限制状态由 LED 指示；当输出电流超过限制电流时自动转为恒流模式，对超负载或故障提供完全保护。
元件清单：安装步骤：1.按照 PCB 标示安装电阻、二极管等，电阻安装前务必用万用表核对阻值确保正确，二极管注意型号、安装方向。
2.依照从小到大、从低到高的原则安装其他元件。
3.注意集成电路的安装方向，电位器可直接安装在板上，也可用配套的插座及连线引到面板安装。
4.全部安装完毕，仔细检查无误后，即可通电试机，通电前务必确保 Q4（D1047）安装了足够大面积的散热片，散热片需与电路绝缘电路调整：左边电位器用于电流调节，右边电位器用于电压调节。
1.将电压调整电位器设在最小位置(逆时针旋到最小) ，调整 RV1（100K 可调电阻），使输出电压为0V 即可（调整中可能会出现负电压并且数值很小，请使用数字万用表进行）。
最大输出电压不需调整，使用 24V 交流输入时，最大输出电压约为 31V 左右。
2.电流标定：使用合适的负载电阻接在输出端，比如 10 欧（确保功率足够），电流电位器旋至最大，电压电位器旋至最小，开机慢慢增加电压至 1V，逆时针调整电流电位器至发光管刚刚发亮，此时电路限制电流为 0.1A，标记下此时电位器的位置。
依次调整至 2V、5V、10V、20V、30V 等数值，即可标定不同的输出电流，计算公式为：I=U/ R，如使用 10 欧负载，当 U 为 30V 时，I=3A （最大输出）。
5v稳压电源与0~30v可调稳压电源
5V稳压电源与0~30v可调稳压电源姓名：**** 专业班级：***** 学号：********20**年**月**日~20**年**月**日摘要：5V稳压电源与0~30v可调稳压电源：输入220v交流电后5V稳压电源可输出5v直流电压, 0~30v可调稳压电源可输出0~30v可调直流电压，为需要供电的元器件提供直流电压。
采用桥式整流电路，电容滤波，和集成稳压块稳压，本电源可输出稳定直流电压，在后续的学习实验中有很大用途。
关键词：交流，直流，整流，稳压1.设计任务：输入220v交流电后可输出5v直流电压,为需要供电的元器件提供直流电压。
输入220v交流电后可输出0~30v中任一直流电压,为需要供电的元器件提供直流电压。
1.1 方案论证见图1-1及图1-2：图1-1图1-21.2 工作原理：5V稳压电源：输入220v交流电后可输出5v直流电压,为需要供电的元器件提供直流电压。
市电进入电源，首先要经过变压器由高压变为低压，滤除高频杂波和同相干扰信号，改变电压。
然后再经过由 4 个二极管组成的桥式电路整流，和大容量的滤波电容滤波后，再经过集成稳压块7805以及电位器后，输出的的电压，才算真正完成所需要的较为纯净的低压直流电压。
各模块功能：①电源变压器：降低电压。
②整流电路：由4只二极管组成的桥式整流电路。
③滤波：用2200UF25V的电解电容1只和一个104的瓷片电容，接在整流电路的后面最基本的将交流转换为直流的电路，在所有需要将交流电转换为直流电的电路中，设置滤波电容会使电子电路的工作性能更加稳定，同时也降低了交变脉动波纹对电子电路的干扰。
安装在整流电路两端用以降低交流脉动波纹系数提升，高效平滑直流输出的一种储能器件，我们把这种器件称其为滤波电容。
滤波电容具有电极性，我们又称其为电解电容。
电解电容的一端为正极，另一端为负极，正极端连接在整流输出电路的正端，负极连接在电路的负端。
滤波电容用在电源整流电路中，用来滤除交流成分。
0-30V可调稳压电源
0-30V 可调稳压电源General DescriptionThis is a high quality power supply with a continuously variable stabilised output adjustable at any value between 0 and 30VDC. The circuit also incorporates an electronic output current limiter that effectively controls the output current from a few milliamperes (2 mA) to the maximum output of three amperes that the circuit can deliver. This feature makes this power supply indispensable in the experimenters laboratory as it is possible to limit the current to the typical maximum that a circuit under test may require, and power it up then, without any fear that it may be damaged if something goes wrong. There is also a visual indication that the current limiter is in operation so that you can see at a glance that your circuit is exceeding or not its preset limits.Technical Specifications - CharacteristicsInput Voltage: ................ 24 VAC Input Current: ................ 3 A (max) Output Voltage: ............. 0-30 V adjustable Output Current: ............. 2 mA-3 A adjustable Output Voltage Ripple: . 0.01 % maximumFEATURES- Reduced dimensions, easy construction, simple operation. - Output voltage easily adjustable. - Output current limiting with visual indication. - Complete protection of the supplied device against over loads and malfunction.How it WorksTo start with, there is a step-down mains transformer with a secondary winding rated at 24 V/3 A, which is connected across the input points of the circuit at pins 1 & 2. (the quality of the supplies output will be directly proportional to the quality of the transformer). The AC voltage of the transformers secondary winding is rectified by the bridge formed by the four diodes D1-D4. The DC voltage taken across the output of the bridge is smoothed by the filter formed by the reservoir capacitor C1 and the resistor R1. The circuit incorporates some unique features which make it quite different from other power supplies of its class. Instead of using a variable feedback arrangement to control the output voltage, our circuit uses a constant gainamplifier to provide the reference voltage necessary for its stable operation. The reference voltage is generated at the output of U1. The circuit operates as follows: The diode D8 is a 5.6 V zener, which here operates at its zero temperature coefficient current. The voltage in the output of U1 gradually increases till the diode D8 is turned on. When this happens the circuit stabilises and the Zener reference voltage (5.6 V) appears across the resistor R5. The current which flows through the non inverting input of the op-amp is negligible, therefore the same current flows through R5 and R6, and as the two resistors have the same value the voltage across the two of them in series will be exactly twice the voltage across each one. Thus the voltage present at the output of the op-amp (pin 6 of U1) is 11.2 V, twice the zeners reference voltage. The integrated circuit U2 has a constant amplification factor of approximately 3 X, according to the formula A=(R11+R12)/R11, and raises the 11.2 V reference voltage to approximately 33 V. The trimmer RV1 and the resistor R10 are used for the adjustment of the output voltages limits so that it can be reduced to 0 V, despite any value tolerances of the other components in the circuit. Another very important feature of the circuit, is the possibility to preset the maximum output current which can be drawn from the p.s.u., effectively converting it from a constant voltage source to a constant current one. To make this possible the circuit detects the voltage drop across a resistor (R7) which is connected in series with the load. The IC responsible for this function of the circuit is U3. The inverting input of U3 is biased at 0 V via R21. At the same time the non inverting input of the same IC can be adjusted to any voltage by means of P2. Let us assume that for a given output of several volts, P2 is set so that the input of the IC is kept at 1 V. If the load is increased the output voltage will be kept constant by the voltage amplifier section of the circuit and the presence of R7 in series with the output will have a negligible effect because of its low value and because of its location outside the feedback loop of the voltage control circuit. While the load is kept constant and the output voltage is not changed the circuit is stable. If the load is increased so that the voltage drop across R7 is greater than 1 V, IC3 is forced into action and the circuit is shifted into the constant current mode. The output of U3 is coupled to the non inverting input of U2 by D9. U2 is responsible for the voltage control and as U3 is coupled to its input the latter can effectively override its function. What happens is that the voltage across R7 is monitored and is not allowed to increase above the preset value (1 V in our example) by reducing the output voltage of the circuit. This is in effect a means of maintaining the output current constant and is so accurate that it is possible to preset the current limit to as low as 2 mA. The capacitor C8 is there to increase the stability of the circuit. Q3 is used to drive the LED whenever the current limiter is activated in order to provide a visual indication of the limiters operation. In order to make it possible for U2 to control the output voltage down to 0 V, it is necessary to provide a negative supply rail and this is done by means of the circuit around C2 & C3. The same negative supply is also used for U3. As U1 is working under fixed conditions it can be run from the unregulated positive supply rail and the earth. The negative supply rail is produced by a simple voltage pump circuit which is stabilised by means of R3 and D7. In order to avoid uncontrolled situations at shut-down there is a protection circuit built around Q1. As soon as the negative supply rail collapses Q1 reMOVes all drive to the output stage. This in effect brings the output voltage to zero as soon as the AC is removed protecting the circuit and the appliances connected to its output. During normal operation Q1 is kept off by means of R14 but when the negative supply rail collapses the transistor is turned on and brings the output of U2 low. The IC has internal protection and can not be damaged because of this effective short circuiting of its output. It is a great advantage in experimental work to be able to kill the output of a power supply without having to wait for the capacitors to discharge and there is also an added protection because the output of many stabilised power supplies tends to rise instantaneously at switch off with disastrous results.ConstructionFirst of all let us consider a few basics in building electronic circuits on a printed circuit board. The board is made of a thin insulating material clad with a thin layer of conductive copper that is shaped in such a way as to form the necessary conductors between the various components of the circuit. The use of a properly designed printed circuit board is very desirable as it speeds construction up considerably and reduces the possibility of making errors. To protect the board during storage from oxidation and assure it gets to you in perfect condition the copper is tinned during manufacturing and covered with a special varnish that protects it from getting oxidised and also makes soldering easier. Soldering the components to the board is the only way to build your circuit and from the way you do it depends greatly your success or failure. This work is not very difficult and if you stick to a few rules you should have no problems. The soldering iron that you use must be light and its power should not exceed the 25 Watts. The tip should be fine and must be kept clean at all times. For this purpose come very handy specially made sponges that are kept wet and from time to time you can wipe thehot tip on them to reMOVe all the residues that tend to accumulate on it. DO NOT file or sandpaper a dirty or worn out tip. If the tip cannot be cleaned, replace it. There are many different types of solder in the market and you should choose a good quality one that contains the necessary flux in its core, to assure a perfect joint every time. DO NOT use soldering flux apart from that which is already included in your solder. Too much flux can cause many problems and is one of the main causes of circuit malfunction. If nevertheless you have to use extra flux, as it is the case when you have to tin copper wires, clean it very thoroughly after you finish your work. In order to solder a component correctly you should do the following: - Clean the component leads with a small piece of emery paper. - Bend them at the correct distance from the components body and insert he component in its place on the board. - You may find sometimes a component with heavier gauge leads than usual, that are too thick to enter in the holes of the p.c. board. In this case use a mini drill to enlarge the holes slightly. Do not make the holes too large as this is going to make soldering difficult afterwards. - Take the hot iron and place its tip on the component lead while holding the end of the solder wire at the point where the lead emerges from the board. The iron tip must touch the lead slightly above the p.c. board. - When the solder starts to melt and flow wait till it covers evenly the area around the hole and the flux boils and gets out from underneath the solder. - The whole operation should not take more than 5 seconds. ReMOVe the iron and allow the solder to cool naturally without blowing on it or moving the component. If everything was done properly the surface of the joint must have a bright metallic finish and its edges should be smoothly ended on the component lead and the board track. If the solder looks dull, cracked, or has the shape of a blob then you have made a dry joint and you should remove the solder (with a pump, or a solder wick) and redo it. Take care not to overheat the tracks as it is very easy to lift them from the board and break them. - When you are soldering a sensitive component it is good practice to hold the lead from the component side of the board with a pair of long-nose pliers to divert any heat that could possibly damage the component. - Make sure that you do not use more solder than it is necessary as you are running the risk of short-circuiting adjacent tracks on the board, especially if they are very close together. - When you finish your work, cut off the excess of the component leads and clean the board thoroughly with a suitable solvent to reMOVe all flux residues that may still remain on it. connections.gif (17,8KB) pcb.gif (60KB) (12,5cm x 8,7cm)As it is recommended start working by identifying the components and separating them in groups. Place first of all the sockets for the ICs and the pins for the external connections and solder them in their places. Continue with the resistors. Remember to mound R7 at a certain distance from the printed circuit board as it tends to become quite hot, especially when the circuit is supplying heavy currents, and this could possibly damage the board. It is also advisable to mount R1 at a certain distance from the surface of the PCB as well. Continue with the capacitors observing the polarity of the electrolytic andfinally solder in place the diodes and the transistors taking care not to overheat them and being at the same time very careful to align them correctly. Mount the power transistor on the heatsink. To do this follow the diagram and remember to use the mica insulator between the transistor body and the heatsink and the special fibber washers to insulate the screws from the heatsink. Remember to place the soldering tag on one of the screws from the side of the transistor body, this is going to be used as the collector lead of the transistor. Use a little amount of Heat Transfer Compound between the transistor and the heatsink to ensure the maximum transfer of heat between them, and tighten the screws as far as they will go. Attach a piece of insulated wire to each lead taking care to make very good joints as the current that flows in this part of the circuit is quite heavy, especially between the emitter and the collector of the transistor. It is convenient to know where you are going to place every thing inside the case that is going to accommodate your power supply, in order to calculate the length of the wires to use between the PCB and the potentiometers, the power transistor and for the input and output connections to the circuit. (It does not really matter if the wires are longer but it makes a much neater project if the wires are trimmed at exactly the length necessary). Connect the potentiometers, the LED and the power transistor and attach two pairs of leads for the input and output connections. Make sure that you follow the circuit diagram very care fully for these connections as there are 15 external connections to the circuit in total and if you make a mistake it may be very difficult to find it afterwards. It is a good idea to use cables of different colours in order to make trouble shooting easier. The external connections are: - 1 & 2 AC input, the secondary of the transformer. - 3 (+) & 4 (-) DC output. - 5, 10 & 12 to P1. - 6, 11 & 13 to P2. - 7 (E), 8 (B), 9 (E) to the power transistor Q4. - The LED should also be placed on the front panel of the case where it is always visible but the pins where it is connected at are not numbered. When all the external connections have been finished make a very careful inspection of the board and clean it to reMOVe soldering flux residues. Make sure that there are no bridges that may short circuit adjacent tracks and if everything seems to be all right connect the input of the circuit with the secondary of a suitable mains transformer. Connect a voltmeter across the output of the circuit and the primary of the transformer to the mains. DO NOT TOUCH ANY PART OF THE CIRCUIT WHILE IT IS UNDER POWER. The voltmeter should measure a voltage between 0 and 30 VDC depending on the setting of P1, and should follow any changes of this setting to indicate that the variable voltage control is working properly. Turning P2 counter-clockwise should turn the LED on, indicating that the current limiter is in operation.AdjustmentsIf you want the output of your supply to be adjustable between 0 and 30 V you should adjust RV1 to make sure that when P1 is at its minimum setting the output of the supply is exactly 0 V. As it is not possible to measure very small values with a conventional panel meter it is better to use a digital meter for this adjustment, and to set it at a very low scale to increase its sensitivity.WarningWhile using electrical parts, handle power supply and equipment with great care, following safety standards as described by international specs and regulations.CAUTIONThis circuit works off the mains and there are 220 VAC present in some of its parts. Voltages above 50 V are DANGEROUS and could even be LETHAL.In order to avoid accidents that could be fatal to you or members of your family please observe the following rules: - DO NOT work if you are tired or in a hurry, double check every thing before connecting your circuit to the mains and be ready - to disconnect it if something looks wrong. - DO NOT touch any part of the circuit when it is under power. - DO NOT leave mains leads exposed. All mains leads should be well insulated. - DO NOT change the fuses with others of higher rating or replace them with wire or aluminium foil. - DO NOT work with wet hands. - If you are wearing a chain, necklace or anything that may be hanging and touch an exposed part of the circuit BE CAREFUL. - ALWAYS use a proper mains lead with the correct plug and earth your circuit properly. - If the case of your project is made of metal make sure that it is properly earthen. - If it is possible use a mains transformer with a 1:1 ratio to isolate your circuit from the mains. - When you are testing a circuit that works off the mains wear shoes with rubber soles, stand on dry non conductive floor - and keep one hand in your pocket or behind your back. - If you take all the above precautions you are reducing the - risks you are taking to a minimum and this way you are protecting - yourself and those around you. - A carefully built and well insulated device does not constitute any danger for its user. - BEWARE: ELECTRICITY CAN KILL IF YOU ARE NOT CAREFUL.If it does not workCheck your work for possible dry joints, bridges across adjacent tracks or soldering flux residues that usually cause problems. Check again all the external connections to and from the circuit to see if there is a mistake there. - See that there are no components missing or inserted in the wrong places. - Make sure that all the polarised components have been soldered the right way round. - Make sure the supply has the correct voltage and is connected the right way round to your circuit. - Check your project for faulty or damaged components. Electronic Diagram.schem.gif (14,8 KB)Parts List.R1 = 2,2 KOhm 1W R3 = 220 Ohm 1/4W R5, R6, R13, R20, R21 = 10 KOhm 1/4W R8, R11 = 27 KOhm 1/4W R10 = 270 KOhm 1/4W R14 = 1,5 KOhm 1/4W R17 = 33 Ohm 1/4W RV1 = 100K trimmer C1 = 3300 uF/50V electrolytic C4 = 100nF polyester C6 = 100pF ceramic C8 = 330pF ceramic D1, D2, D3, D4 = 1N5402,3,4 diode 2A - RAX GI837U D7, D8 = 5,6V Zener D11 = 1N4001 diode 1A Q2 = 2N2219 NPN transistor Q4 = 2N3055 NPN power transistor D12 = LED diode R2 = 82 Ohm 1/4W R4 = 4,7 KOhm 1/4W R7 = 0,47 Ohm 5W R9, R19 = 2,2 KOhm 1/4W R12, R18 = 56KOhm 1/4W R15, R16 = 1 KOhm 1/4W R22 = 3,9 KOhm 1/4W P1, P2 = 10KOhm linear pontesiometer C2, C3 = 47uF/50V electrolytic C5 = 200nF polyester C7 = 10uF/50V electrolytic C9 = 100pF ceramic D5, D6 = 1N4148 D9, D10 = 1N4148 Q1 = BC548, NPN transistor or BC547 Q3 = BC557, PNP transistor or BC327 U1, U2, U3 = TL081, operational amplifier。
简单易制的0-30V（10A）可调稳压电源
简单易制的0-30V（10A）可调稳压电源简单易制的0-30V(10A)可调稳压电源“工欲善其事，必先利其器”！对于电子爱好者来说，能拥有一台性能优良的电源，应该说是可以从“源”头上保证了制作作品的成功率和优良性能的发挥！本文介绍一种简单易制的可调稳压电源，可以在0-30V的范围内稳定的输出最大10A的电流，基本上可以满足常见的电子制作需要。
而且其电路非常简洁、制作简单，性能优良稳定、成本低廉，非常适合电子爱好者制作，下面简要介绍一下其电路原理、制作方法和注意事项。
电路原理本电源在保证功能适用、性能稳定的前提下对电路尽量简化，这样既可以降低制作工作量和难度，又可以提高制作的成功率。
电路如图（1），主要由Q1、Q2、IC1组成的调整稳压电路和IC2组成的-1.25V生成电路，以及IC4组成的输入电压自动切换控制电路和以Q3、M1、M2为主组成的输出显示、指示电路等4部分电路完成整机功能。
由电路图可以清楚的发现本机稳压部分采用了常见的工频变压器整流、滤波、线性稳压的工作原理，之所以没有采用高效率、轻便的开关电源电路模式，主要是因为考虑到作为实验用供电电源，对其主要的要求是输出宽可调电压范围、大输出电流供应、低输出纹波电压、电源纯净度高，对于电源效率要求并不高，而开关电源虽然效率高，但其输出波形干扰纹波大、可调范围窄，因此采用传统的线性稳压电路。
下面介绍一下整机电路的工作原理。
从J1、J2输入的交流电网220V电压经K1、F1输入电源变压器B1的初级，从其次级分别输出9V、12V、24V的交流电压。
输出的9V交流电压经D2整流、C7、C8滤波后加在IC2/LM337的输入端，在其输出端产生-1.25V的电压，R6作为IC2的负载，C9使IC2输出端的电压更为稳定、纯净。
设置此部分电路的目的是为了用其产生的-1.25V电压抵消IC1/LM317输出端最低只能到达+1.25V的电压，从而使整机输出电压可以从0V起输出，而并非是从+1.25V开始输出，这样可以满足部分需要低于1.25V的低电压的试验场合的需要。